/**
 * ScienceDirect Style - E-Book Publishing Platform
 * Clean, scholarly design with orange and blue accents
 */

/* ========================================
   CSS Variables / Design Tokens
   ======================================== */
:root {
    /* Primary Colors */
    --color-primary: #007398;
    --color-primary-dark: #005a75;
    --color-primary-light: #e6f3f7;

    /* Accent Colors - Lighter Orange */
    --color-accent: #F5A623;
    --color-accent-dark: #E8960F;
    --color-accent-light: #FFF8EE;

    /* Neutral Colors */
    --color-background: #F5F6F7;
    --color-white: #ffffff;
    --color-gray-50: #fafafa;
    --color-gray-100: #f5f5f5;
    --color-gray-200: #eeeeee;
    --color-gray-300: #e0e0e0;
    --color-gray-400: #bdbdbd;
    --color-gray-500: #9e9e9e;
    --color-gray-600: #757575;
    --color-gray-700: #616161;
    --color-gray-800: #424242;
    --color-gray-900: #212121;

    /* Text Colors */
    --color-text: #2b2b2b;
    --color-text-secondary: #505050;
    --color-text-muted: #757575;
    --color-link: #007398;
    --color-link-hover: #005a75;

    /* Status Colors */
    --color-success: #2e7d32;
    --color-warning: #f9a825;
    --color-error: #c62828;
    --color-open-access: #F5A623;

    /* Shadows */
    --shadow-sm: 0 1px 2px rgba(0, 0, 0, 0.05);
    --shadow-md: 0 2px 4px rgba(0, 0, 0, 0.1);
    --shadow-lg: 0 4px 12px rgba(0, 0, 0, 0.15);
    --shadow-card: 0 1px 3px rgba(0, 0, 0, 0.08);

    /* Typography */
    --font-family: 'Source Sans Pro', -apple-system, BlinkMacSystemFont, 'Segoe UI', Roboto, sans-serif;
    --font-size-xs: 0.75rem;
    --font-size-sm: 0.875rem;
    --font-size-base: 1rem;
    --font-size-lg: 1.125rem;
    --font-size-xl: 1.25rem;
    --font-size-2xl: 1.5rem;
    --font-size-3xl: 1.875rem;

    /* Spacing */
    --spacing-xs: 0.25rem;
    --spacing-sm: 0.5rem;
    --spacing-md: 1rem;
    --spacing-lg: 1.5rem;
    --spacing-xl: 2rem;
    --spacing-2xl: 3rem;

    /* Border Radius */
    --radius-sm: 2px;
    --radius-md: 4px;
    --radius-lg: 8px;

    /* Transitions */
    --transition-fast: 150ms ease;
    --transition-normal: 250ms ease;

    /* Layout */
    --container-max-width: 1280px;
    --sidebar-width: 280px;
    --header-height: 64px;
}

/* ========================================
   Reset & Base Styles
   ======================================== */
*,
*::before,
*::after {
    box-sizing: border-box;
    margin: 0;
    padding: 0;
}

html {
    font-size: 16px;
    -webkit-font-smoothing: antialiased;
    -moz-osx-font-smoothing: grayscale;
}

body {
    font-family: var(--font-family);
    font-size: var(--font-size-base);
    line-height: 1.6;
    color: var(--color-text);
    background-color: var(--color-background);
    min-height: 100vh;
}

a {
    color: var(--color-link);
    text-decoration: none;
    transition: color var(--transition-fast);
}

a:hover {
    color: var(--color-link-hover);
    text-decoration: underline;
}

img {
    max-width: 100%;
    height: auto;
    display: block;
}

ul,
ol {
    list-style: none;
}

button,
input,
select,
textarea {
    font-family: 'Segoe UI', Tahoma, Geneva, Verdana, sans-serif;
    font-size: 15px;
}

/* ========================================
   Global Form Elements - ScienceDirect Style
   ======================================== */

/* All Input Fields */
input[type="text"],
input[type="email"],
input[type="password"],
input[type="number"],
input[type="tel"],
input[type="url"],
input[type="search"],
input[type="date"],
textarea,
select {
    padding: 10px 14px;
    border: 1px solid #333;
    border-radius: 0;
    font-size: 15px;
    font-family: 'Segoe UI', Tahoma, Geneva, Verdana, sans-serif;
    transition: all 0.2s ease;
    background-color: #fff;
    color: #333;
    width: 100%;
}

input[type="text"]:focus,
input[type="email"]:focus,
input[type="password"]:focus,
input[type="number"]:focus,
input[type="tel"]:focus,
input[type="url"]:focus,
input[type="search"]:focus,
input[type="date"]:focus,
textarea:focus,
select:focus {
    outline: none;
    border-color: #E8A735;
    box-shadow: 0 0 0 3px rgba(232, 167, 53, 0.15);
}

input::placeholder,
textarea::placeholder {
    color: #757575;
    font-size: 14px;
}

/* Select Dropdown */
select {
    cursor: pointer;
    appearance: none;
    background-image: url("data:image/svg+xml,%3Csvg xmlns='http://www.w3.org/2000/svg' width='12' height='12' viewBox='0 0 12 12'%3E%3Cpath fill='%23333' d='M6 8L1 3h10z'/%3E%3C/svg%3E");
    background-repeat: no-repeat;
    background-position: right 12px center;
    padding-right: 36px;
}

/* Textarea */
textarea {
    min-height: 120px;
    resize: vertical;
    line-height: 1.5;
}

/* All Buttons - ScienceDirect Style */
button,
.btn,
input[type="submit"],
input[type="button"] {
    padding: 10px 24px;
    border: 1px solid #333;
    border-radius: 0;
    font-size: 14px;
    font-weight: 500;
    font-family: 'Segoe UI', Tahoma, Geneva, Verdana, sans-serif;
    cursor: pointer;
    transition: all 0.2s ease;
    display: inline-flex;
    align-items: center;
    justify-content: center;
    gap: 8px;
    text-decoration: none;
    background-color: transparent;
    color: #333;
}

button:hover,
.btn:hover,
input[type="submit"]:hover,
input[type="button"]:hover {
    background-color: #f5f5f5;
    border-color: #E8A735;
    text-decoration: none;
}

button:focus,
.btn:focus,
input[type="submit"]:focus,
input[type="button"]:focus {
    outline: none;
    border-color: #E8A735;
    box-shadow: 0 0 0 3px rgba(232, 167, 53, 0.15);
}

/* Primary Button */
.btn-primary,
button.primary,
input[type="submit"].primary {
    background-color: #007398;
    border-color: #007398;
    color: #fff;
}

.btn-primary:hover,
button.primary:hover,
input[type="submit"].primary:hover {
    background-color: #005a75;
    border-color: #005a75;
    color: #fff;
}

/* Secondary/Accent Button */
.btn-secondary,
.btn-accent,
button.secondary {
    background-color: #E8A735;
    border-color: #E8A735;
    color: #fff;
}

.btn-secondary:hover,
.btn-accent:hover,
button.secondary:hover {
    background-color: #d49730;
    border-color: #d49730;
    color: #fff;
}

/* Outline Button */
.btn-outline {
    background-color: transparent;
    border-color: #333;
    color: #333;
}

.btn-outline:hover {
    background-color: #f5f5f5;
    border-color: #E8A735;
}

/* Form Labels */
label {
    display: block;
    margin-bottom: 6px;
    font-size: 14px;
    font-weight: 500;
    color: #333;
}

/* Form Groups */
.form-group {
    margin-bottom: 20px;
}

/* Checkbox & Radio - ScienceDirect Style */
input[type="checkbox"],
input[type="radio"] {
    width: 18px;
    height: 18px;
    accent-color: #E8A735;
    cursor: pointer;
}

/* ========================================
   Typography
   ======================================== */
h1,
h2,
h3,
h4,
h5,
h6 {
    font-weight: 600;
    line-height: 1.3;
    color: var(--color-text);
    margin-bottom: var(--spacing-md);
}

h1 {
    font-size: var(--font-size-3xl);
}

h2 {
    font-size: var(--font-size-2xl);
}

h3 {
    font-size: var(--font-size-xl);
}

h4 {
    font-size: var(--font-size-lg);
}

p {
    margin-bottom: var(--spacing-md);
}

/* ========================================
   Layout Components
   ======================================== */
.container {
    max-width: var(--container-max-width);
    margin: 0 auto;
    padding: 0 var(--spacing-lg);
}

.page-wrapper {
    display: flex;
    min-height: calc(100vh - var(--header-height));
}

.main-content {
    flex: 1;
    padding: var(--spacing-xl);
    background-color: var(--color-background);
}

.content-with-sidebar {
    display: grid;
    grid-template-columns: var(--sidebar-width) 1fr;
    gap: var(--spacing-xl);
    max-width: var(--container-max-width);
    margin: 0 auto;
    padding: var(--spacing-xl) var(--spacing-lg);
}

/* ========================================
   Header / Navigation
   ======================================== */
.header {
    background-color: var(--color-white);
    border-bottom: 1px solid var(--color-gray-200);
    position: sticky;
    top: 0;
    z-index: 1000;
}

.header-top {
    background-color: var(--color-gray-900);
    padding: var(--spacing-xs) 0;
}

.header-top .container {
    display: flex;
    justify-content: space-between;
    align-items: center;
}

.header-top-links {
    display: flex;
    align-items: center;
    gap: var(--spacing-lg);
}

.header-top-links a,
.header-top-links span,
.header-top-links button {
    color: var(--color-gray-300);
    font-size: var(--font-size-sm);
}

.header-top-links a:hover {
    color: var(--color-white);
    text-decoration: none;
}

/* Country Switcher */
.country-switcher {
    position: relative;
    display: inline-block;
}

.country-switcher .country-btn {
    background: none;
    border: none;
    color: var(--color-gray-300);
    cursor: pointer;
    padding: 0;
    font-size: var(--font-size-sm);
    display: flex;
    align-items: center;
    gap: 4px;
}

.country-switcher .country-btn:hover {
    color: var(--color-white);
}

.country-dropdown {
    display: none;
    position: absolute;
    right: 0;
    top: calc(100% + 5px);
    background: #fff;
    border: 1px solid #ddd;
    border-radius: 8px;
    box-shadow: 0 8px 24px rgba(0,0,0,0.2);
    z-index: 9999;
    min-width: 280px;
    overflow: hidden;
}

.country-search-box {
    padding: 10px;
    border-bottom: 1px solid #eee;
    position: relative;
    background: #f9fafb;
}

.country-search-box input {
    width: 100%;
    padding: 8px 12px 8px 35px;
    border: 1px solid #ddd;
    border-radius: 6px;
    font-size: 13px;
    outline: none;
    color: #1a1a1a !important;
    background: #fff !important;
}

.country-search-box input:focus {
    border-color: #007398;
    box-shadow: 0 0 0 2px rgba(0,115,152,0.1);
}

.country-search-box i.fa-search {
    position: absolute;
    left: 22px;
    top: 50%;
    transform: translateY(-50%);
    color: #888;
    font-size: 12px;
}

.country-suggestions {
    position: absolute;
    top: 100%;
    left: 10px;
    right: 10px;
    background: white;
    border: 2px solid #007398;
    border-radius: 8px;
    box-shadow: 0 4px 15px rgba(0,0,0,0.2);
    z-index: 100;
    max-height: 250px;
    overflow-y: auto;
    display: none;
    margin-top: 5px;
}

.country-suggestions.show {
    display: block;
}

.suggestion-header {
    padding: 8px 12px;
    background: #f0f7ff;
    font-size: 11px;
    color: #007398;
    font-weight: 600;
    border-bottom: 1px solid #e0e0e0;
}

.country-suggestion-item {
    padding: 12px 15px;
    cursor: pointer;
    border-bottom: 1px solid #f0f0f0;
    font-size: 14px;
    transition: background 0.15s;
    color: #1a1a1a !important;
    background: #fff;
}

.country-suggestion-item:last-child {
    border-bottom: none;
}

.country-suggestion-item:hover,
.country-suggestion-item.highlighted {
    background: #e6f3f7;
}

.country-suggestion-item .name {
    font-weight: 500;
    color: #1a1a1a !important;
}

.country-suggestion-item .name mark {
    background: #fef08a;
    padding: 0 2px;
    border-radius: 2px;
}

.no-suggestion {
    padding: 20px;
    text-align: center;
    color: #888;
}

.no-suggestion i {
    font-size: 24px;
    opacity: 0.5;
    display: block;
    margin-bottom: 8px;
}

.country-list {
    max-height: 350px;
    overflow-y: auto;
    background: #fff;
}

.country-list::-webkit-scrollbar {
    width: 6px;
}

.country-list::-webkit-scrollbar-track {
    background: #f1f1f1;
}

.country-list::-webkit-scrollbar-thumb {
    background: #ccc;
    border-radius: 3px;
}

.country-list::-webkit-scrollbar-thumb:hover {
    background: #999;
}

.country-item {
    display: block;
    padding: 12px 15px;
    color: #1a1a1a !important;
    text-decoration: none;
    font-size: 14px;
    border-bottom: 1px solid #eee;
    background: #fff;
    opacity: 1 !important;
}

.country-item:hover {
    background: #f0f7ff;
}

.country-item.active {
    background: #e6f3f7;
    font-weight: 600;
    color: #007398 !important;
}

.country-item.hidden {
    display: none !important;
}

.country-name {
    font-weight: 500;
    color: #1a1a1a !important;
}

.no-results {
    padding: 20px;
    text-align: center;
    color: #888;
    font-size: 13px;
}

/* Country dropdown link styles - Override header-top-links gray color */
.header-top-links .country-dropdown .country-item,
.header-top-links .country-dropdown .country-item:visited,
.header-top-links .country-dropdown .country-item:link {
    color: #1a1a1a !important;
    opacity: 1 !important;
}

.header-top-links .country-dropdown .country-item:hover {
    color: #1a1a1a !important;
    background: #f0f7ff;
}

.header-top-links .country-dropdown .country-item.active {
    color: #007398 !important;
    background: #e6f3f7;
}

.header-top-links .country-dropdown .country-name {
    color: #1a1a1a !important;
}

.header-main {
    padding: var(--spacing-md) 0;
}

.header-main .container {
    display: flex;
    align-items: center;
    gap: var(--spacing-xl);
}

.logo {
    display: flex;
    align-items: center;
    gap: var(--spacing-sm);
    font-size: var(--font-size-xl);
    font-weight: 700;
    color: #333;
}

.logo:hover {
    text-decoration: none;
    color: #333;
}

.logo-icon {
    width: 40px;
    height: 40px;
    background-color: transparent;
    border-radius: 0;
    display: flex;
    align-items: center;
    justify-content: center;
    color: #333;
}

/* Search Bar - ScienceDirect Style */
.search-container {
    flex: 1;
    max-width: 600px;
}

.search-form {
    display: flex;
    position: relative;
    align-items: center;
    gap: 10px;
}

.search-input {
    flex: 1;
    padding: 10px 14px;
    border: 1px solid #333;
    border-radius: 0;
    font-size: 15px;
    font-family: 'Segoe UI', Tahoma, Geneva, Verdana, sans-serif;
    transition: all 0.2s ease;
    background-color: #fff;
}

.search-input:focus {
    outline: none;
    border-color: #E8A735;
    box-shadow: 0 0 0 3px rgba(232, 167, 53, 0.15);
}

.search-input::placeholder {
    color: #757575;
    font-size: 14px;
}

.search-btn {
    padding: 10px 20px;
    background-color: transparent;
    color: #333;
    border: 1px solid #333;
    border-radius: 0;
    font-size: 14px;
    font-weight: 500;
    cursor: pointer;
    transition: all 0.2s ease;
    display: flex;
    align-items: center;
    gap: 6px;
    white-space: nowrap;
}

.search-btn:hover {
    background-color: #f5f5f5;
    border-color: #E8A735;
    color: #333;
}

.search-btn:focus {
    outline: none;
    border-color: #E8A735;
    box-shadow: 0 0 0 3px rgba(232, 167, 53, 0.15);
}

/* Search Autocomplete Suggestions - ScienceDirect Style */
.search-suggestions {
    position: absolute;
    top: calc(100% + 2px);
    left: 0;
    right: 100px;
    background: #fff;
    border: 1px solid #ddd;
    border-top: 3px solid #E8A735;
    border-radius: 0;
    box-shadow: 0 4px 12px rgba(0, 0, 0, 0.12);
    z-index: 1000;
    max-height: 400px;
    overflow-y: auto;
    display: none;
}

.search-suggestions.active {
    display: block;
}

.search-suggestion-item {
    display: flex;
    align-items: center;
    padding: 12px 16px;
    cursor: pointer;
    transition: background-color 0.15s;
    border-bottom: 1px solid var(--color-gray-100);
    text-decoration: none;
    color: inherit;
}

.search-suggestion-item:last-child {
    border-bottom: none;
}

.search-suggestion-item:hover,
.search-suggestion-item.active {
    background-color: var(--color-primary-light);
}

.search-suggestion-icon {
    width: 32px;
    height: 32px;
    display: flex;
    align-items: center;
    justify-content: center;
    margin-right: 12px;
    border-radius: 4px;
    font-size: 14px;
}

.search-suggestion-icon.type-book {
    background: #e3f2fd;
    color: #1976d2;
}

.search-suggestion-icon.type-subject {
    background: #f3e5f5;
    color: #7b1fa2;
}

.search-suggestion-icon.type-author {
    background: #e8f5e9;
    color: #388e3c;
}

.search-suggestion-icon.type-isbn {
    background: #fff3e0;
    color: #f57c00;
}

.search-suggestion-text {
    flex: 1;
    overflow: hidden;
}

.search-suggestion-label {
    font-size: 14px;
    font-weight: 500;
    color: var(--color-text);
    white-space: nowrap;
    overflow: hidden;
    text-overflow: ellipsis;
}

.search-suggestion-type {
    font-size: 11px;
    color: var(--color-text-muted);
    text-transform: uppercase;
    letter-spacing: 0.5px;
}

.search-no-results {
    padding: 20px;
    text-align: center;
    color: var(--color-text-muted);
    font-size: 14px;
}

.search-loading {
    padding: 20px;
    text-align: center;
    color: var(--color-text-muted);
}

.search-loading i {
    animation: spin 1s linear infinite;
}

@keyframes spin {
    from {
        transform: rotate(0deg);
    }

    to {
        transform: rotate(360deg);
    }
}

/* ========================================
   Hero Banners - Peek Carousel like Jaypee
   ======================================== */
.hero-banners {
    background: #0d1f2d;
    padding: 0;
    width: 100%;
    overflow: hidden;
}

/* Banner with Animated Book Sidebars */
.banner-with-sidebars {
    display: flex;
    align-items: stretch;
    width: 100%;
    background: #0d1f2d;
    height: 500px;
    max-height: 500px;
    overflow: hidden;
}

.banner-sidebar {
    width: 160px;
    min-width: 160px;
    height: 100%;
    background: linear-gradient(180deg, #0d1f2d 0%, #152a3d 100%);
    overflow: hidden;
    position: relative;
}

.banner-sidebar::before,
.banner-sidebar::after {
    content: '';
    position: absolute;
    left: 0;
    right: 0;
    height: 50px;
    z-index: 2;
    pointer-events: none;
}

.banner-sidebar::before {
    top: 0;
    background: linear-gradient(to bottom, #0d1f2d, transparent);
}

.banner-sidebar::after {
    bottom: 0;
    background: linear-gradient(to top, #0d1f2d, transparent);
}

.sidebar-books-scroll {
    display: flex;
    flex-direction: column;
    gap: 12px;
    padding: 10px;
    animation: scrollUp 25s linear infinite;
}

.sidebar-books-scroll.scroll-reverse {
    animation: scrollDown 25s linear infinite;
}

@keyframes scrollUp {
    0% {
        transform: translateY(0);
    }
    100% {
        transform: translateY(-50%);
    }
}

@keyframes scrollDown {
    0% {
        transform: translateY(-50%);
    }
    100% {
        transform: translateY(0);
    }
}

.sidebar-book {
    display: block;
    border-radius: 4px;
    overflow: hidden;
    transition: transform 0.3s ease, box-shadow 0.3s ease;
    box-shadow: 0 4px 8px rgba(0,0,0,0.3);
}

.sidebar-book:hover {
    transform: scale(1.08);
    box-shadow: 0 6px 16px rgba(0,0,0,0.5);
    z-index: 5;
}

.sidebar-book img {
    width: 100%;
    height: auto;
    min-height: 130px;
    max-height: 150px;
    object-fit: cover;
    display: block;
}

.banner-slider {
    position: relative;
    flex: 1;
    overflow: hidden;
    background: #0d1f2d;
}

.banner-slides-wrapper {
    position: relative;
    width: 100%;
    overflow: hidden;
}

.banner-track {
    display: flex;
    align-items: center;
    justify-content: center;
    gap: 20px;
    transition: transform 0.5s ease;
    width: 100%;
}

.banner-slide {
    position: absolute;
    top: 0;
    left: 0;
    width: 100%;
    opacity: 0;
    transition: opacity 0.5s ease;
    pointer-events: none;
}

.banner-slide.active {
    opacity: 1;
    pointer-events: auto;
    z-index: 10;
    position: relative;
}

.banner-slide.prev,
.banner-slide.next {
    opacity: 0;
}

.banner-grid {
    display: block;
    width: 100%;
}

.banner-card {
    display: block;
    width: 100%;
    overflow: hidden;
    border-radius: 0;
    transition: all 0.3s ease;
    background: #0d1f2d;
}

.banner-slide.active .banner-card {
    /* No shadow for full width */
}

.banner-card:hover {
    opacity: 1;
}

.banner-card img {
    width: 100%;
    height: auto;
    min-height: 350px;
    max-height: 500px;
    object-fit: contain;
    object-position: center;
    display: block;
}

.banner-placeholder {
    display: flex;
    align-items: center;
    justify-content: center;
    height: 450px;
    border: 2px dashed #ccc;
    border-radius: 0;
}

.banner-placeholder .placeholder-content {
    text-align: center;
    color: #999;
}

.banner-placeholder .placeholder-content i {
    font-size: 48px;
    margin-bottom: 10px;
    display: block;
}

.banner-placeholder .placeholder-content span {
    font-size: 14px;
}

/* Navigation Arrows */
.banner-nav {
    position: absolute;
    top: 50%;
    transform: translateY(-50%);
    width: 44px;
    height: 44px;
    background: white;
    border: none;
    border-radius: 50%;
    box-shadow: 0 2px 10px rgba(0, 0, 0, 0.15);
    cursor: pointer;
    z-index: 10;
    display: flex;
    align-items: center;
    justify-content: center;
    font-size: 16px;
    color: #333;
    transition: all 0.3s ease;
}

.banner-nav:hover {
    background: var(--color-primary);
    color: white;
    box-shadow: 0 4px 15px rgba(0, 0, 0, 0.2);
}

.banner-prev {
    left: 15px;
}

.banner-next {
    right: 15px;
}

/* Dots Navigation */
.banner-dots {
    display: flex;
    justify-content: center;
    gap: 10px;
    margin-top: 20px;
}

.banner-dot {
    width: 10px;
    height: 10px;
    background: #ccc;
    border-radius: 50%;
    cursor: pointer;
    transition: all 0.3s ease;
}

.banner-dot:hover {
    background: #999;
}

.banner-dot.active {
    background: var(--color-primary);
    transform: scale(1.2);
}

/* Responsive */
@media (max-width: 992px) {
    .banner-prev {
        left: 10px;
    }

    .banner-next {
        right: 10px;
    }
}

@media (max-width: 992px) {
    .banner-with-sidebars {
        height: 400px;
        max-height: 400px;
    }

    .banner-sidebar {
        width: 90px;
        min-width: 90px;
    }

    .sidebar-book img {
        min-height: 100px;
        max-height: 120px;
    }
}

@media (max-width: 768px) {
    .banner-with-sidebars {
        height: auto;
        max-height: none;
    }

    .banner-sidebar {
        display: none;
    }

    .banner-grid {
        grid-template-columns: 1fr;
        gap: 16px;
    }

    .banner-slides-wrapper {
        min-height: auto;
    }

    .banner-card img {
        min-height: 280px;
        max-height: 380px;
    }

    .banner-placeholder {
        height: 200px;
    }

    .banner-nav {
        width: 36px;
        height: 36px;
        font-size: 14px;
    }

    .banner-prev {
        left: 5px;
    }

    .banner-next {
        right: 5px;
    }
}

@media (max-width: 576px) {
    .hero-banners {
        padding: 0;
    }

    .banner-slides-wrapper {
        min-height: auto;
    }

    .banner-card img {
        min-height: 180px;
        max-height: 280px;
    }

    .banner-placeholder {
        height: 160px;
    }
}

/* Search Autocomplete */
.search-autocomplete {
    position: absolute;
    top: 100%;
    left: 0;
    right: 0;
    background: var(--color-white);
    border: 1px solid var(--color-gray-300);
    border-radius: 0 0 var(--radius-md) var(--radius-md);
    box-shadow: var(--shadow-lg);
    max-height: 400px;
    overflow-y: auto;
    display: none;
    z-index: 100;
}

.search-autocomplete.active {
    display: block;
}

.autocomplete-item {
    display: flex;
    gap: var(--spacing-md);
    padding: var(--spacing-md);
    border-bottom: 1px solid var(--color-gray-100);
    cursor: pointer;
    transition: background-color var(--transition-fast);
    text-decoration: none;
    color: inherit;
}

.autocomplete-item:hover {
    background-color: var(--color-gray-50);
    text-decoration: none;
}

.autocomplete-item img {
    width: 50px;
    height: 70px;
    object-fit: cover;
    border: 1px solid var(--color-gray-200);
}

.autocomplete-info h4 {
    font-size: var(--font-size-sm);
    margin-bottom: var(--spacing-xs);
    color: var(--color-primary);
}

.autocomplete-info p {
    font-size: var(--font-size-xs);
    color: var(--color-text-muted);
    margin: 0;
}

/* Header Actions */
.header-actions {
    display: flex;
    align-items: center;
    gap: var(--spacing-md);
}

/* Header Buttons - ScienceDirect Style */
.header-btn {
    display: inline-flex;
    align-items: center;
    gap: 6px;
    padding: 8px 18px;
    background: transparent;
    border: 1px solid #333;
    border-radius: 0;
    color: #333;
    font-size: 14px;
    font-weight: 500;
    font-family: 'Segoe UI', Tahoma, Geneva, Verdana, sans-serif;
    cursor: pointer;
    transition: all 0.2s ease;
    text-decoration: none;
}

.header-btn:hover {
    background-color: #f5f5f5;
    border-color: #E8A735;
    color: #333;
    text-decoration: none;
}

.header-btn:focus {
    outline: none;
    border-color: #E8A735;
    box-shadow: 0 0 0 3px rgba(232, 167, 53, 0.15);
}

.header-btn.primary {
    background-color: #007398;
    border-color: #007398;
    color: #fff;
}

.header-btn.primary:hover {
    background-color: #005a75;
    border-color: #005a75;
    color: #fff;
}

/* Main Navigation */
.main-nav {
    background-color: var(--color-white);
    border-bottom: 1px solid var(--color-gray-200);
}

.nav-list {
    display: flex;
    gap: var(--spacing-xl);
}

.nav-item {
    position: relative;
}

.nav-link {
    display: block;
    padding: var(--spacing-md) 0;
    color: var(--color-text);
    font-weight: 500;
    border-bottom: 3px solid transparent;
    transition: all var(--transition-fast);
}

.nav-link:hover,
.nav-link.active {
    color: var(--color-primary);
    text-decoration: none;
    border-bottom-color: var(--color-accent);
}

/* Mobile Menu Toggle */
.menu-toggle {
    display: none;
    background: none;
    border: none;
    font-size: 1.5rem;
    cursor: pointer;
    color: var(--color-text);
}

/* ========================================
   Hero Section
   ======================================== */
.hero {
    background: linear-gradient(135deg, var(--color-primary) 0%, var(--color-primary-dark) 100%);
    color: var(--color-white);
    padding: var(--spacing-2xl) 0;
}

.hero-content {
    max-width: 700px;
}

.hero h1 {
    color: var(--color-white);
    font-size: 2.5rem;
    margin-bottom: var(--spacing-md);
}

.hero p {
    font-size: var(--font-size-lg);
    opacity: 0.9;
    margin-bottom: var(--spacing-lg);
}

.hero-search {
    max-width: 500px;
}

.hero-search .search-input {
    border-color: transparent;
    padding: var(--spacing-md) var(--spacing-lg);
    font-size: var(--font-size-lg);
}

/* ========================================
   Subject Tabs / Categories
   ======================================== */
.subject-tabs {
    background-color: var(--color-white);
    padding: var(--spacing-lg) 0;
    border-bottom: 1px solid var(--color-gray-200);
}

.tabs-list {
    display: flex;
    flex-wrap: wrap;
    gap: var(--spacing-sm);
}

.tab-item {
    padding: var(--spacing-sm) var(--spacing-md);
    background-color: var(--color-gray-100);
    border-radius: var(--radius-md);
    color: var(--color-text);
    font-size: var(--font-size-sm);
    transition: all var(--transition-fast);
}

.tab-item:hover,
.tab-item.active {
    background-color: var(--color-primary);
    color: var(--color-white);
    text-decoration: none;
}

/* ========================================
   Cards
   ======================================== */
.card {
    background-color: var(--color-white);
    border-radius: var(--radius-md);
    box-shadow: var(--shadow-card);
    overflow: hidden;
    transition: box-shadow var(--transition-fast);
}

.card:hover {
    box-shadow: var(--shadow-md);
}

/* Book Card - List Style */
.book-card {
    display: flex;
    gap: var(--spacing-lg);
    padding: var(--spacing-lg);
    border-bottom: 1px solid var(--color-gray-100);
    background-color: var(--color-white);
}

.book-card:last-child {
    border-bottom: none;
}

.book-card-cover {
    flex-shrink: 0;
    width: 120px;
}

.book-card-cover img {
    width: 100%;
    height: 160px;
    object-fit: cover;
    border: 1px solid var(--color-gray-200);
}

.book-card-content {
    flex: 1;
    min-width: 0;
}

.book-card-type {
    display: inline-block;
    font-size: var(--font-size-xs);
    color: var(--color-text-muted);
    text-transform: uppercase;
    letter-spacing: 0.5px;
    margin-bottom: var(--spacing-xs);
}

.book-card-title {
    font-size: var(--font-size-lg);
    font-weight: 600;
    margin-bottom: var(--spacing-xs);
}

.book-card-title a {
    color: var(--color-primary);
}

.book-card-title a:hover {
    text-decoration: underline;
}

.book-card-subtitle {
    color: var(--color-text-secondary);
    font-size: var(--font-size-sm);
    margin-bottom: var(--spacing-sm);
}

.book-card-authors {
    font-size: var(--font-size-sm);
    color: var(--color-text-muted);
    margin-bottom: var(--spacing-sm);
}

.book-card-authors a {
    color: var(--color-link);
}

.book-card-meta {
    display: flex;
    flex-wrap: wrap;
    gap: var(--spacing-md);
    font-size: var(--font-size-sm);
    color: var(--color-text-muted);
    margin-bottom: var(--spacing-sm);
}

.book-card-description {
    font-size: var(--font-size-sm);
    color: var(--color-text-secondary);
    line-height: 1.5;
    margin: 0;
}

/* Open Access Badge */
.badge-open-access {
    display: inline-flex;
    align-items: center;
    gap: var(--spacing-xs);
    padding: 2px 8px;
    background-color: var(--color-accent-light);
    color: var(--color-accent);
    border-radius: var(--radius-sm);
    font-size: var(--font-size-xs);
    font-weight: 600;
}

.badge-open-access i {
    font-size: 10px;
}

/* Grid Cards - Professional 3D Book Style */
.book-grid {
    display: grid;
    grid-template-columns: repeat(5, 1fr);
    gap: 35px 30px;
    padding: 30px 0;
}

@media (max-width: 1400px) {
    .book-grid {
        grid-template-columns: repeat(4, 1fr);
    }
}

@media (max-width: 1100px) {
    .book-grid {
        grid-template-columns: repeat(3, 1fr);
        gap: 30px 25px;
    }
}

@media (max-width: 768px) {
    .book-grid {
        grid-template-columns: repeat(2, 1fr);
        gap: 25px 20px;
    }
}

@media (max-width: 500px) {
    .book-grid {
        grid-template-columns: 1fr;
        gap: 20px;
    }
}

.book-grid-card {
    background-color: var(--color-white);
    border-radius: 12px;
    box-shadow: 0 2px 12px rgba(0, 0, 0, 0.08);
    overflow: visible;
    transition: all 0.3s ease;
    padding: 16px;
    position: relative;
    border: 1px solid var(--color-gray-200);
}

.book-grid-card:hover {
    box-shadow: 0 8px 24px rgba(0, 0, 0, 0.12);
    transform: translateY(-4px);
    border-color: var(--color-gray-300);
}

.book-grid-card-cover {
    position: relative;
    display: flex;
    justify-content: center;
    align-items: center;
    margin-bottom: 12px;
    perspective: 1000px;
    height: 180px;
}

/* 3D Book Effect */
.book-grid-card-cover img {
    width: auto;
    height: 160px;
    max-width: 100%;
    object-fit: contain;
    border-radius: 4px;
    box-shadow: 4px 4px 12px rgba(0, 0, 0, 0.15);
    transform: rotateY(-8deg);
    transition: all 0.3s ease;
}

.book-grid-card:hover .book-grid-card-cover img {
    transform: rotateY(-12deg) translateY(-4px);
    box-shadow: 8px 8px 20px rgba(0, 0, 0, 0.2);
}

/* Category Badge - Simple Style */
.book-grid-card-badge {
    position: absolute;
    top: 8px;
    left: 8px;
    z-index: 10;
}

.book-grid-card-badge .badge-category {
    display: inline-block;
    padding: 3px 8px;
    font-size: 10px;
    font-weight: 600;
    text-transform: uppercase;
    letter-spacing: 0.3px;
    color: var(--color-gray-600);
    background: var(--color-white);
    border: 1px solid var(--color-gray-300);
    border-radius: 3px;
}

.book-grid-card-badge .badge-open-access {
    color: #059669;
    background: #ecfdf5;
    border-color: #a7f3d0;
}

.book-grid-card-content {
    padding: 0;
    text-align: left;
}

.book-grid-card-title {
    font-size: 14px;
    font-weight: 600;
    margin-bottom: 6px;
    line-height: 1.4;
    display: -webkit-box;
    -webkit-line-clamp: 2;
    -webkit-box-orient: vertical;
    overflow: hidden;
}

.book-grid-card-title a {
    color: #0891b2;
    text-decoration: none;
    transition: color 0.2s;
}

.book-grid-card-title a:hover {
    color: #0e7490;
    text-decoration: underline;
}

.book-grid-card-authors {
    font-size: 12px;
    color: #6b7280;
    margin: 0 0 4px 0;
    display: -webkit-box;
    -webkit-line-clamp: 1;
    -webkit-box-orient: vertical;
    overflow: hidden;
}

.book-grid-card-year {
    font-size: 12px;
    color: #9ca3af;
    margin: 0;
}

.book-grid-card-meta {
    font-size: 12px;
    color: #6b7280;
    margin-bottom: 6px;
    line-height: 1.4;
}

/* Book Price */
.book-grid-card-price {
    font-size: 22px;
    font-weight: 700;
    color: #111827;
    margin-top: 12px;
    letter-spacing: -0.5px;
}

.book-grid-card-price .original-price {
    font-size: 14px;
    color: #9ca3af;
    text-decoration: line-through;
    margin-left: 8px;
    font-weight: 400;
}

/* ========================================
   Sidebar
   ======================================== */
.sidebar {
    background-color: var(--color-white);
    border-radius: var(--radius-md);
    box-shadow: var(--shadow-card);
    padding: var(--spacing-lg);
    height: fit-content;
    position: sticky;
    top: calc(var(--header-height) + var(--spacing-lg));
}

.sidebar-section {
    margin-bottom: var(--spacing-xl);
}

.sidebar-section:last-child {
    margin-bottom: 0;
}

.sidebar-title {
    font-size: var(--font-size-sm);
    font-weight: 600;
    color: var(--color-text);
    text-transform: uppercase;
    letter-spacing: 0.5px;
    margin-bottom: var(--spacing-md);
    padding-bottom: var(--spacing-sm);
    border-bottom: 2px solid var(--color-accent);
}

/* Filter Select */
.filter-select {
    width: 100%;
    padding: var(--spacing-sm) var(--spacing-md);
    border: 1px solid var(--color-gray-300);
    border-radius: var(--radius-md);
    font-size: var(--font-size-sm);
    background-color: var(--color-white);
    cursor: pointer;
}

.filter-select:focus {
    outline: none;
    border-color: var(--color-primary);
}

/* Filter Checkboxes */
.filter-list {
    display: flex;
    flex-direction: column;
    gap: var(--spacing-sm);
}

.filter-item {
    display: flex;
    align-items: center;
    gap: var(--spacing-sm);
}

.filter-item input[type="checkbox"] {
    width: 16px;
    height: 16px;
    accent-color: var(--color-primary);
}

.filter-item label {
    font-size: var(--font-size-sm);
    color: var(--color-text-secondary);
    cursor: pointer;
}

.filter-item label:hover {
    color: var(--color-primary);
}

.filter-count {
    color: var(--color-text-muted);
    font-size: var(--font-size-xs);
}

/* Apply Filters Button */
.filter-btn {
    width: 100%;
    padding: var(--spacing-sm) var(--spacing-md);
    background-color: var(--color-accent);
    color: var(--color-white);
    border: none;
    border-radius: var(--radius-md);
    font-weight: 600;
    cursor: pointer;
    transition: background-color var(--transition-fast);
    margin-top: var(--spacing-md);
}

.filter-btn:hover {
    background-color: var(--color-accent-dark);
}

.clear-filters {
    display: block;
    text-align: center;
    margin-top: var(--spacing-sm);
    font-size: var(--font-size-sm);
    color: var(--color-text-muted);
}

/* ========================================
   A-Z Navigation
   ======================================== */
.az-nav {
    background-color: var(--color-white);
    padding: var(--spacing-md);
    border-radius: var(--radius-md);
    margin-bottom: var(--spacing-lg);
    box-shadow: var(--shadow-card);
}

.az-nav-title {
    font-size: var(--font-size-sm);
    font-weight: 600;
    margin-bottom: var(--spacing-sm);
}

.az-list {
    display: flex;
    flex-wrap: wrap;
    gap: var(--spacing-xs);
}

.az-item {
    display: flex;
    align-items: center;
    justify-content: center;
    width: 32px;
    height: 32px;
    border: 1px solid var(--color-gray-300);
    border-radius: var(--radius-sm);
    font-size: var(--font-size-sm);
    font-weight: 500;
    color: var(--color-text);
    transition: all var(--transition-fast);
}

.az-item:hover,
.az-item.active {
    background-color: var(--color-primary);
    border-color: var(--color-primary);
    color: var(--color-white);
    text-decoration: none;
}

.az-item.disabled {
    color: var(--color-gray-400);
    pointer-events: none;
}

/* ========================================
   Results Header
   ======================================== */
.results-header {
    display: flex;
    justify-content: space-between;
    align-items: center;
    margin-bottom: var(--spacing-lg);
    padding-bottom: var(--spacing-md);
    border-bottom: 1px solid var(--color-gray-200);
}

.results-count {
    font-size: var(--font-size-sm);
    color: var(--color-text-secondary);
}

.results-count strong {
    color: var(--color-text);
}

.results-sort {
    display: flex;
    align-items: center;
    gap: var(--spacing-sm);
}

.results-sort label {
    font-size: var(--font-size-sm);
    color: var(--color-text-secondary);
}

.sort-select {
    padding: var(--spacing-xs) var(--spacing-md);
    border: 1px solid var(--color-gray-300);
    border-radius: var(--radius-md);
    font-size: var(--font-size-sm);
    background-color: var(--color-white);
}

/* ========================================
   Book List Container
   ======================================== */
.books-list {
    background-color: var(--color-white);
    border-radius: var(--radius-md);
    box-shadow: var(--shadow-card);
}

/* ========================================
   Book Detail Page
   ======================================== */
.book-detail {
    background-color: var(--color-white);
    border-radius: var(--radius-md);
    box-shadow: var(--shadow-card);
    overflow: hidden;
}

.book-detail-header {
    display: grid;
    grid-template-columns: 250px 1fr;
    gap: var(--spacing-xl);
    padding: var(--spacing-xl);
    background-color: var(--color-gray-50);
    border-bottom: 1px solid var(--color-gray-200);
}

.book-detail-cover {
    perspective: 1000px;
    display: flex;
    justify-content: center;
    align-items: center;
    padding: 20px;
}

.book-detail-cover img {
    width: 200px;
    height: auto;
    max-height: 300px;
    object-fit: contain;
    border-radius: 8px;
    box-shadow:
        15px 15px 40px rgba(0, 0, 0, 0.2),
        0 0 6px rgba(0, 0, 0, 0.1);
    transform: rotateY(-12deg) rotateX(4deg);
    transition: all 0.4s ease;
    transform-style: preserve-3d;
}

.book-detail-cover:hover img {
    transform: rotateY(-18deg) rotateX(6deg) translateY(-10px);
    box-shadow:
        20px 30px 60px rgba(0, 0, 0, 0.25),
        0 0 10px rgba(0, 0, 0, 0.12);
}

.book-detail-info h1 {
    font-size: var(--font-size-2xl);
    margin-bottom: var(--spacing-xs);
}

.book-detail-subtitle {
    font-size: var(--font-size-lg);
    color: var(--color-text-secondary);
    margin-bottom: var(--spacing-md);
}

.book-detail-authors {
    margin-bottom: var(--spacing-lg);
}

.book-detail-authors a {
    font-weight: 500;
}

.book-detail-badges {
    display: flex;
    gap: var(--spacing-sm);
    margin-bottom: var(--spacing-lg);
}

.book-detail-actions {
    display: flex;
    gap: var(--spacing-md);
}

.btn {
    display: inline-flex;
    align-items: center;
    gap: var(--spacing-sm);
    padding: var(--spacing-sm) var(--spacing-lg);
    border-radius: var(--radius-md);
    font-weight: 600;
    font-size: var(--font-size-sm);
    cursor: pointer;
    transition: all var(--transition-fast);
    text-decoration: none;
    border: 2px solid transparent;
}

.btn-primary {
    background-color: var(--color-accent);
    color: var(--color-white);
    border-color: var(--color-accent);
}

.btn-primary:hover {
    background-color: var(--color-accent-dark);
    border-color: var(--color-accent-dark);
    color: var(--color-white);
    text-decoration: none;
}

.btn-secondary {
    background-color: var(--color-white);
    color: var(--color-primary);
    border-color: var(--color-primary);
}

.btn-secondary:hover {
    background-color: var(--color-primary);
    color: var(--color-white);
    text-decoration: none;
}

.btn-outline {
    background-color: transparent;
    color: var(--color-gray-600);
    border-color: var(--color-gray-300);
}

.btn-outline:hover {
    border-color: var(--color-primary);
    color: var(--color-primary);
    text-decoration: none;
}

/* Book Detail Tabs */
.book-detail-tabs {
    border-bottom: 1px solid var(--color-gray-200);
}

.tabs-nav {
    display: flex;
    gap: 0;
    padding: 0 var(--spacing-lg);
}

.tab-btn {
    padding: var(--spacing-md) var(--spacing-lg);
    background: none;
    border: none;
    border-bottom: 3px solid transparent;
    font-size: var(--font-size-base);
    font-weight: 500;
    color: var(--color-text-secondary);
    cursor: pointer;
    transition: all var(--transition-fast);
}

.tab-btn:hover,
.tab-btn.active {
    color: var(--color-primary);
    border-bottom-color: var(--color-accent);
}

.tab-content {
    padding: var(--spacing-xl);
}

.tab-pane {
    display: none;
}

.tab-pane.active {
    display: block;
}

/* Book Metadata Table */
.book-meta-table {
    width: 100%;
    border-collapse: collapse;
}

.book-meta-table tr {
    border-bottom: 1px solid var(--color-gray-100);
}

.book-meta-table th,
.book-meta-table td {
    padding: var(--spacing-md);
    text-align: left;
}

.book-meta-table th {
    width: 200px;
    font-weight: 600;
    color: var(--color-text);
    background-color: var(--color-gray-50);
}

.book-meta-table td {
    color: var(--color-text-secondary);
}

/* Key Features List */
.key-features {
    list-style: none;
}

.key-features li {
    position: relative;
    padding-left: var(--spacing-lg);
    margin-bottom: var(--spacing-sm);
    color: var(--color-text-secondary);
}

.key-features li::before {
    content: '';
    position: absolute;
    left: 0;
    top: 8px;
    width: 8px;
    height: 8px;
    background-color: var(--color-accent);
    border-radius: 50%;
}

/* Table of Contents */
.toc-list {
    counter-reset: chapter;
}

.toc-item {
    padding: var(--spacing-md);
    border-bottom: 1px solid var(--color-gray-100);
    display: flex;
    align-items: center;
    gap: var(--spacing-md);
}

.toc-item::before {
    counter-increment: chapter;
    content: counter(chapter);
    display: flex;
    align-items: center;
    justify-content: center;
    width: 28px;
    height: 28px;
    background-color: var(--color-gray-100);
    border-radius: 50%;
    font-size: var(--font-size-sm);
    font-weight: 600;
    color: var(--color-text-muted);
    flex-shrink: 0;
}

/* Chapters List with Buy Option */
.chapters-list {
    border: 1px solid var(--color-gray-200);
    border-radius: var(--radius-md);
    overflow: hidden;
}

.chapter-row {
    display: flex;
    align-items: center;
    justify-content: space-between;
    padding: 16px 20px;
    border-bottom: 1px solid var(--color-gray-100);
    transition: background 0.2s;
}

.chapter-row:last-child {
    border-bottom: none;
}

.chapter-row:hover {
    background: var(--color-gray-50);
}

.chapter-info {
    display: flex;
    align-items: center;
    gap: 16px;
    flex: 1;
}

.chapter-num {
    width: 36px;
    height: 36px;
    background: linear-gradient(135deg, #1e3a8a 0%, #3b82f6 100%);
    color: white;
    border-radius: 50%;
    display: flex;
    align-items: center;
    justify-content: center;
    font-weight: 600;
    font-size: 14px;
    flex-shrink: 0;
}

.chapter-details {
    display: flex;
    flex-direction: column;
    gap: 4px;
}

.chapter-title-link {
    font-weight: 500;
    color: var(--color-text);
    text-decoration: none;
}

.chapter-title-link:hover {
    color: var(--color-primary);
}

.chapter-meta {
    font-size: 13px;
    color: var(--color-text-muted);
    display: flex;
    align-items: center;
    gap: 12px;
}

.chapter-meta .free-badge {
    background: #d1fae5;
    color: #065f46;
    padding: 2px 8px;
    border-radius: 10px;
    font-size: 11px;
    font-weight: 500;
}

.chapter-meta .purchased-badge {
    background: #dbeafe;
    color: #1e40af;
    padding: 2px 8px;
    border-radius: 10px;
    font-size: 11px;
    font-weight: 500;
}

.chapter-actions {
    flex-shrink: 0;
}

/* Related Books Section */
.related-books {
    margin-top: var(--spacing-xl);
    padding: var(--spacing-xl);
    background-color: var(--color-white);
    border-radius: var(--radius-md);
    box-shadow: var(--shadow-card);
}

.related-books h2 {
    margin-bottom: var(--spacing-lg);
}

/* ========================================
   Pagination
   ======================================== */
.pagination {
    display: flex;
    justify-content: center;
    margin-top: var(--spacing-xl);
}

.pagination-list {
    display: flex;
    align-items: center;
    gap: var(--spacing-xs);
}

.pagination-link,
.pagination-prev,
.pagination-next {
    display: flex;
    align-items: center;
    justify-content: center;
    min-width: 36px;
    height: 36px;
    padding: 0 var(--spacing-sm);
    border: 1px solid var(--color-gray-300);
    border-radius: var(--radius-md);
    font-size: var(--font-size-sm);
    color: var(--color-text);
    transition: all var(--transition-fast);
}

.pagination-link:hover,
.pagination-prev:hover,
.pagination-next:hover {
    background-color: var(--color-gray-50);
    border-color: var(--color-primary);
    color: var(--color-primary);
    text-decoration: none;
}

.pagination-link.active {
    background-color: var(--color-primary);
    border-color: var(--color-primary);
    color: var(--color-white);
}

.pagination-ellipsis {
    padding: 0 var(--spacing-sm);
    color: var(--color-text-muted);
}

/* ========================================
   Homepage Sections
   ======================================== */
.section {
    padding: 60px 0;
}

.section-header {
    display: flex;
    justify-content: space-between;
    align-items: center;
    margin-bottom: 30px;
    padding-bottom: 15px;
    border-bottom: 2px solid #f3f4f6;
}

.section-title {
    font-size: 26px;
    font-weight: 700;
    margin: 0;
    color: #1f2937;
}

.section-link {
    font-size: 14px;
    font-weight: 500;
    color: var(--color-primary);
    display: flex;
    align-items: center;
    gap: 6px;
    transition: all 0.2s;
}

.section-link:hover {
    text-decoration: none;
    color: #0e7490;
    gap: 10px;
}

/* Featured Section */
.featured-section {
    background-color: var(--color-white);
}

/* Subject Cards for Homepage */
.subjects-grid {
    display: grid;
    grid-template-columns: repeat(auto-fill, minmax(250px, 1fr));
    gap: var(--spacing-md);
}

.subject-card {
    display: flex;
    align-items: center;
    gap: var(--spacing-md);
    padding: var(--spacing-md);
    background-color: var(--color-white);
    border-radius: var(--radius-md);
    box-shadow: var(--shadow-card);
    transition: all var(--transition-fast);
}

.subject-card:hover {
    box-shadow: var(--shadow-md);
    text-decoration: none;
}

.subject-card-icon {
    width: 48px;
    height: 48px;
    display: flex;
    align-items: center;
    justify-content: center;
    background-color: transparent;
    border-radius: var(--radius-md);
    color: #333;
    font-size: var(--font-size-xl);
}

.subject-card-content h3 {
    font-size: var(--font-size-sm);
    margin: 0 0 var(--spacing-xs) 0;
    color: var(--color-text);
}

.subject-card-content p {
    font-size: var(--font-size-xs);
    color: var(--color-text-muted);
    margin: 0;
}

/* ========================================
   Footer
   ======================================== */
.footer {
    background-color: var(--color-gray-900);
    color: var(--color-gray-300);
    padding: var(--spacing-2xl) 0 var(--spacing-lg);
    margin-top: auto;
}

.footer-grid {
    display: grid;
    grid-template-columns: repeat(4, 1fr);
    gap: var(--spacing-xl);
    margin-bottom: var(--spacing-xl);
}

.footer-col h4 {
    color: var(--color-white);
    font-size: var(--font-size-base);
    margin-bottom: var(--spacing-md);
}

.footer-links {
    display: flex;
    flex-direction: column;
    gap: var(--spacing-sm);
}

.footer-links a {
    color: var(--color-gray-400);
    font-size: var(--font-size-sm);
}

.footer-links a:hover {
    color: var(--color-white);
    text-decoration: none;
}

.footer-bottom {
    padding-top: var(--spacing-lg);
    border-top: 1px solid var(--color-gray-700);
    display: flex;
    justify-content: space-between;
    align-items: center;
}

.footer-copyright {
    font-size: var(--font-size-sm);
    color: var(--color-gray-500);
}

.footer-social {
    display: flex;
    gap: var(--spacing-md);
}

.footer-social a {
    color: var(--color-gray-400);
    font-size: var(--font-size-lg);
}

.footer-social a:hover {
    color: var(--color-white);
    text-decoration: none;
}

/* ========================================
   Utility Classes
   ======================================== */
.text-center {
    text-align: center;
}

.text-right {
    text-align: right;
}

.text-muted {
    color: var(--color-text-muted);
}

.text-primary {
    color: var(--color-primary);
}

.text-accent {
    color: var(--color-accent);
}

.mt-1 {
    margin-top: var(--spacing-sm);
}

.mt-2 {
    margin-top: var(--spacing-md);
}

.mt-3 {
    margin-top: var(--spacing-lg);
}

.mb-1 {
    margin-bottom: var(--spacing-sm);
}

.mb-2 {
    margin-bottom: var(--spacing-md);
}

.mb-3 {
    margin-bottom: var(--spacing-lg);
}

.d-flex {
    display: flex;
}

.align-center {
    align-items: center;
}

.justify-between {
    justify-content: space-between;
}

.gap-1 {
    gap: var(--spacing-sm);
}

.gap-2 {
    gap: var(--spacing-md);
}

/* Alert Messages */
.alert {
    padding: var(--spacing-md);
    border-radius: var(--radius-md);
    margin-bottom: var(--spacing-lg);
}

.alert-success {
    background-color: #e8f5e9;
    color: var(--color-success);
    border: 1px solid #c8e6c9;
}

.alert-error {
    background-color: #ffebee;
    color: var(--color-error);
    border: 1px solid #ffcdd2;
}

.alert-warning {
    background-color: #fff8e1;
    color: #f57c00;
    border: 1px solid #ffe082;
}

/* Free Shipping Badge */
.free-shipping {
    color: #2e7d32;
    font-weight: 500;
}

small.free-shipping {
    color: #2e7d32;
    font-weight: 500;
}

/* Empty State */
.empty-state {
    text-align: center;
    padding: var(--spacing-2xl);
    color: var(--color-text-muted);
}

.empty-state i {
    font-size: 3rem;
    margin-bottom: var(--spacing-md);
    color: var(--color-gray-400);
}

.empty-state h3 {
    margin-bottom: var(--spacing-sm);
}

/* ========================================
   Responsive Design
   ======================================== */
@media (max-width: 1024px) {
    .content-with-sidebar {
        grid-template-columns: 1fr;
    }

    .sidebar {
        position: static;
        order: -1;
    }

    .footer-grid {
        grid-template-columns: repeat(2, 1fr);
    }

    .book-detail-header {
        grid-template-columns: 150px 1fr;
    }
}

@media (max-width: 768px) {
    :root {
        --header-height: 56px;
    }

    .header-top {
        display: none;
    }

    .header-main .container {
        flex-wrap: wrap;
    }

    .search-container {
        order: 3;
        flex: 0 0 100%;
        max-width: 100%;
        margin-top: var(--spacing-md);
    }

    .header-actions {
        margin-left: auto;
    }

    .menu-toggle {
        display: block;
    }

    .main-nav {
        display: none;
    }

    .main-nav.active {
        display: block;
    }

    .nav-list {
        flex-direction: column;
        gap: 0;
    }

    .nav-link {
        padding: var(--spacing-md);
        border-bottom: 1px solid var(--color-gray-200);
    }

    .hero h1 {
        font-size: 1.75rem;
    }

    .book-card {
        flex-direction: column;
    }

    .book-card-cover {
        width: 100%;
        max-width: 150px;
    }

    .book-detail-header {
        grid-template-columns: 1fr;
        text-align: center;
    }

    .book-detail-cover {
        max-width: 200px;
        margin: 0 auto;
    }

    .book-detail-actions {
        justify-content: center;
        flex-wrap: wrap;
    }

    .footer-grid {
        grid-template-columns: 1fr;
    }

    .footer-bottom {
        flex-direction: column;
        gap: var(--spacing-md);
        text-align: center;
    }

    .az-item {
        width: 28px;
        height: 28px;
        font-size: var(--font-size-xs);
    }

    .tabs-nav {
        overflow-x: auto;
        padding: 0;
    }

    .tab-btn {
        white-space: nowrap;
        padding: var(--spacing-sm) var(--spacing-md);
    }

    .subjects-grid {
        grid-template-columns: 1fr;
    }
}

@media (max-width: 480px) {
    .container {
        padding: 0 var(--spacing-md);
    }

    .book-grid {
        grid-template-columns: repeat(2, 1fr);
        gap: var(--spacing-md);
    }

    .results-header {
        flex-direction: column;
        gap: var(--spacing-md);
        align-items: flex-start;
    }

    .btn {
        width: 100%;
        justify-content: center;
    }

    .book-detail-actions .btn {
        flex: 1;
    }
}

/* ========================================
   Static Page Content Styles
   ======================================== */
.page-content {
    max-width: 900px;
    margin: 0 auto;
    padding: var(--spacing-xl);
    background: var(--color-white);
    border-radius: var(--radius-lg);
    box-shadow: var(--shadow-card);
}

.page-content h2 {
    color: var(--color-primary);
    font-size: var(--font-size-2xl);
    margin-bottom: var(--spacing-md);
    padding-bottom: var(--spacing-md);
    border-bottom: 2px solid var(--color-accent);
}

.page-content h3 {
    color: var(--color-gray-800);
    font-size: var(--font-size-xl);
    margin: var(--spacing-xl) 0 var(--spacing-md) 0;
}

.page-content h4 {
    color: var(--color-gray-700);
    font-size: var(--font-size-lg);
    margin: var(--spacing-lg) 0 var(--spacing-sm) 0;
}

.page-content p {
    color: var(--color-text-secondary);
    line-height: 1.8;
    margin-bottom: var(--spacing-md);
}

.page-content p.lead {
    font-size: var(--font-size-lg);
    color: var(--color-text);
    margin-bottom: var(--spacing-lg);
}

.page-content ul,
.page-content ol {
    margin: var(--spacing-md) 0 var(--spacing-lg) var(--spacing-lg);
    color: var(--color-text-secondary);
    line-height: 1.8;
}

.page-content li {
    margin-bottom: var(--spacing-sm);
}

.page-content strong {
    color: var(--color-text);
}

.page-content a {
    color: var(--color-primary);
    text-decoration: underline;
}

.page-content a:hover {
    color: var(--color-accent);
}

/* Feature Grid for Pages */
.page-content .features-grid {
    display: grid;
    grid-template-columns: repeat(auto-fit, minmax(250px, 1fr));
    gap: var(--spacing-lg);
    margin: var(--spacing-lg) 0;
}

.page-content .feature-box {
    padding: var(--spacing-lg);
    background: var(--color-background);
    border-radius: var(--radius-lg);
    border-left: 4px solid var(--color-accent);
    transition: all var(--transition-fast);
}

.page-content .feature-box:hover {
    box-shadow: var(--shadow-md);
    transform: translateY(-2px);
}

.page-content .feature-box h4 {
    color: var(--color-primary);
    margin: 0 0 var(--spacing-sm) 0;
    display: flex;
    align-items: center;
    gap: var(--spacing-sm);
}

.page-content .feature-box h4 i {
    color: var(--color-accent);
}

.page-content .feature-box p {
    margin: 0;
    font-size: var(--font-size-sm);
}

/* FAQ Styles */
.page-content .faq-item {
    background: var(--color-background);
    padding: var(--spacing-lg);
    border-radius: var(--radius-md);
    margin-bottom: var(--spacing-md);
    border-left: 3px solid var(--color-primary);
}

.page-content .faq-item h4 {
    color: var(--color-primary);
    margin: 0 0 var(--spacing-sm) 0;
    font-size: var(--font-size-base);
}

.page-content .faq-item p {
    margin: 0;
    font-size: var(--font-size-sm);
}

/* Text Utilities */
.text-muted {
    color: var(--color-text-muted) !important;
}

.text-center {
    text-align: center;
}

/* Subscription Badge */
.subscription-badge {
    display: inline-flex;
    align-items: center;
    gap: 4px;
    background: linear-gradient(135deg, #FFD700, #FFA500);
    color: #000;
    padding: 2px 10px;
    border-radius: 12px;
    font-size: 11px;
    font-weight: 600;
}

.subscription-badge i {
    color: #000;
}

/* Page Wrapper */
.page-wrapper {
    padding: var(--spacing-xl) 0;
    min-height: 60vh;
    background: var(--color-background);
}

/* Breadcrumb for pages */
.page-breadcrumb {
    font-size: var(--font-size-sm);
    color: var(--color-text-muted);
    margin-bottom: var(--spacing-md);
    padding-bottom: var(--spacing-md);
    border-bottom: 1px solid var(--color-gray-200);
}

.page-breadcrumb a {
    color: var(--color-primary);
}

@media (max-width: 768px) {
    .page-content {
        padding: var(--spacing-md);
        margin: 0 var(--spacing-md);
    }

    .page-content h2 {
        font-size: var(--font-size-xl);
    }

    .page-content .features-grid {
        grid-template-columns: 1fr;
    }
}

/* ========================================
   ScienceDirect Style Footer Section
   ======================================== */
.science-section {
    padding: var(--spacing-2xl) 0;
    background-color: var(--color-white);
    border-top: 1px solid var(--color-gray-200);
}

.science-header {
    margin-bottom: var(--spacing-xl);
    padding-bottom: var(--spacing-md);
    border-bottom: 1px solid var(--color-gray-200);
}

.science-header h2 {
    font-size: var(--font-size-2xl);
    color: var(--color-text);
    margin: 0;
}

.science-header p {
    color: var(--color-text-secondary);
    font-size: var(--font-size-sm);
    margin-top: var(--spacing-xs);
    max-width: 800px;
}

.science-grid {
    display: grid;
    grid-template-columns: repeat(3, 1fr);
    gap: var(--spacing-2xl);
}

.science-col h3 {
    font-size: var(--font-size-base);
    color: var(--color-gray-600);
    margin-bottom: var(--spacing-lg);
    font-weight: 600;
}

/* Link Lists */
.science-links {
    display: flex;
    flex-direction: column;
    gap: var(--spacing-sm);
}

.science-links a {
    color: var(--color-link);
    font-size: var(--font-size-sm);
}

.science-links a:hover {
    text-decoration: underline;
}

/* Article List */
.article-list {
    display: flex;
    flex-direction: column;
    gap: var(--spacing-lg);
}

.article-item {
    display: flex;
    flex-direction: column;
    gap: var(--spacing-xs);
}

.article-title {
    color: var(--color-link);
    font-weight: 600;
    font-size: var(--font-size-base);
    line-height: 1.4;
    text-decoration: none;
}

.article-title:hover {
    text-decoration: underline;
}

.article-journal {
    color: var(--color-text-secondary);
    font-size: var(--font-size-xs);
    font-style: italic;
}

.article-meta {
    color: var(--color-text-muted);
    font-size: var(--font-size-xs);
}

@media (max-width: 900px) {
    .science-grid {
        grid-template-columns: 1fr;
        gap: var(--spacing-xl);
    }
}

/* ========================================
   Section Promotional Banners (Jaypee Style)
   Banner Left + Books 4x2 Grid Right
   ======================================== */
.section-with-banner {
    display: block;
}

.section-with-banner.has-banner {
    display: flex !important;
    flex-direction: row !important;
    gap: 24px;
    align-items: stretch;
}

/* Banner - Fixed width on left side */
.section-promo-banner {
    flex: 0 0 260px;
    width: 260px;
    min-width: 260px;
    max-width: 260px;
    background: #fff;
    border-radius: 8px;
    overflow: hidden;
    box-shadow: 0 2px 12px rgba(0,0,0,0.1);
    border: 1px solid #e5e7eb;
    display: flex;
    flex-direction: column;
    align-self: stretch;
}

.promo-banner-link {
    display: flex;
    flex-direction: column;
    height: 100%;
    text-decoration: none;
    color: inherit;
}

.promo-banner-link:hover .promo-banner-img img {
    transform: scale(1.03);
}

.promo-banner-img {
    flex: 1;
    overflow: hidden;
    background: #f0f4f8;
    display: flex;
    align-items: center;
    justify-content: center;
}

.promo-banner-img img {
    width: 100%;
    height: 100%;
    object-fit: cover;
    display: block;
    transition: transform 0.3s ease;
}

/* Text Content Below Image */
.promo-banner-content {
    padding: 16px;
    background: #fff;
    flex-shrink: 0;
}

.promo-banner-content h3 {
    font-size: 16px;
    font-weight: 700;
    margin: 0 0 8px 0;
    line-height: 1.3;
    color: #1e3a5f;
}

.promo-banner-content p {
    font-size: 12px;
    margin: 0;
    color: #4b5563;
    line-height: 1.6;
    display: -webkit-box;
    -webkit-line-clamp: 8;
    -webkit-box-orient: vertical;
    overflow: hidden;
}

.promo-btn {
    display: inline-block;
    background: var(--color-primary);
    color: white;
    padding: 8px 16px;
    border-radius: 4px;
    font-size: 12px;
    font-weight: 600;
    margin-top: 12px;
    transition: background 0.2s;
}

.promo-btn:hover {
    background: var(--color-primary-dark);
}

/* Books grid - 4 columns, auto rows - MUST wrap */
.section-with-banner.has-banner .book-grid {
    flex: 1 1 auto !important;
    display: grid !important;
    grid-template-columns: repeat(4, 1fr) !important;
    grid-auto-rows: auto !important;
    gap: 20px !important;
    padding: 0 !important;
    align-content: start;
}

.section-with-banner.has-banner .book-grid .book-grid-card {
    margin: 0 !important;
    width: 100% !important;
    padding: 12px !important;
}

/* Smaller book cover in section with banner */
.section-with-banner.has-banner .book-grid-card-cover {
    height: 180px !important;
}

.section-with-banner.has-banner .book-grid-card-cover img {
    max-height: 160px !important;
}

.section-with-banner.has-banner .book-grid-card-title {
    font-size: 13px !important;
    line-height: 1.3 !important;
}

.section-with-banner.has-banner .book-grid-card-meta {
    font-size: 11px !important;
}

/* Responsive for section banners */
@media (max-width: 1400px) {
    .section-with-banner.has-banner .book-grid {
        grid-template-columns: repeat(4, 1fr) !important;
        gap: 16px !important;
    }
}

@media (max-width: 1200px) {
    .section-promo-banner {
        flex: 0 0 220px;
        width: 220px;
        min-width: 220px;
        max-width: 220px;
    }

    .section-with-banner.has-banner .book-grid {
        grid-template-columns: repeat(3, 1fr) !important;
    }
}

@media (max-width: 992px) {
    .section-promo-banner {
        flex: 0 0 200px;
        width: 200px;
        min-width: 200px;
        max-width: 200px;
    }

    .section-with-banner.has-banner .book-grid {
        grid-template-columns: repeat(2, 1fr) !important;
    }
}

@media (max-width: 768px) {
    .section-with-banner.has-banner {
        flex-direction: column !important;
    }

    .section-promo-banner {
        flex: none;
        width: 100%;
        min-width: 100%;
        max-width: 100%;
        margin-bottom: 20px;
    }

    .section-with-banner.has-banner .book-grid {
        grid-template-columns: repeat(2, 1fr) !important;
        width: 100%;
    }

    .promo-banner-img {
        max-height: 200px;
    }
}

@media (max-width: 480px) {
    .section-with-banner.has-banner .book-grid {
        grid-template-columns: repeat(2, 1fr) !important;
        gap: 12px !important;
    }
}