/* ========================================
   银灯文学 - CSS样式系统
   版本: v1.0
   设计理念: 新古典书香风格
   ======================================== */

/* ========================================
   1. CSS变量与设计令牌
   ======================================== */
:root {
    /* 银灯文学色系 */
    --ink-primary: #8B4513;
    --ink-secondary: #D2691E;
    --paper-warm: #FAF3E8;
    --paper-light: #FFF8F0;
    --text-primary: #2C1810;
    --text-secondary: #6B5344;
    --text-muted: #9A8B7A;
    --border-soft: #E8DFD0;
    --shadow-warm: rgba(139, 69, 19, 0.1);

    /* 功能色 */
    --success-green: #5D8A4C;
    --warning-amber: #C9971A;
    --error-red: #B54B4B;
    --info-blue: #4A7C9B;

    /* 字体 */
    --font-display: "Noto Serif SC", "Source Han Serif CN", "SimSun", serif;
    --font-body: "LXGW WenKai", "Noto Sans SC", "PingFang SC", -apple-system, BlinkMacSystemFont, sans-serif;
    --font-mono: "JetBrains Mono", "Fira Code", monospace;

    /* 字体大小 */
    --text-xs: 0.75rem;
    --text-sm: 0.875rem;
    --text-base: 1rem;
    --text-lg: 1.125rem;
    --text-xl: 1.25rem;
    --text-2xl: 1.5rem;
    --text-3xl: 1.875rem;
    --text-4xl: 2.25rem;

    /* 间距 */
    --space-1: 0.25rem;
    --space-2: 0.5rem;
    --space-3: 0.75rem;
    --space-4: 1rem;
    --space-5: 1.25rem;
    --space-6: 1.5rem;
    --space-8: 2rem;
    --space-10: 2.5rem;
    --space-12: 3rem;
    --space-16: 4rem;
    --space-20: 5rem;

    /* 阴影 */
    --shadow-sm: 0 1px 2px rgba(139, 69, 19, 0.05);
    --shadow-md: 0 4px 6px rgba(139, 69, 19, 0.08);
    --shadow-lg: 0 10px 20px rgba(139, 69, 19, 0.1);
    --shadow-xl: 0 20px 40px rgba(139, 69, 19, 0.12);
    --shadow-card: 0 2px 8px rgba(139, 69, 19, 0.06);
    --shadow-hover: 0 8px 24px rgba(139, 69, 19, 0.12);

    /* 圆角 */
    --radius-sm: 0.375rem;
    --radius-md: 0.5rem;
    --radius-lg: 0.75rem;
    --radius-xl: 1rem;
    --radius-full: 9999px;

    /* 动画 */
    --transition-fast: 150ms ease;
    --transition-normal: 300ms ease;
    --transition-slow: 500ms ease;
    --transition-spring: 500ms cubic-bezier(0.34, 1.56, 0.64, 1);

    /* 容器 */
    --container-max: 1400px;
    --navbar-height: 70px;
}

/* ========================================
   2. 基础样式重置
   ======================================== */
*, *::before, *::after {
    margin: 0;
    padding: 0;
    box-sizing: border-box;
}

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

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

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

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

button {
    font-family: inherit;
    cursor: pointer;
    border: none;
    background: none;
}

ul, ol {
    list-style: none;
}

input, textarea, select {
    font-family: inherit;
    font-size: inherit;
}

/* ========================================
   3. 容器与布局
   ======================================== */
.container {
    width: 100%;
    max-width: var(--container-max);
    margin: 0 auto;
    padding: 0 var(--space-6);
}

.main-content {
    min-height: calc(100vh - var(--navbar-height));
    padding-top: var(--navbar-height);
}

/* ========================================
   4. 导航栏
   ======================================== */
.navbar {
    position: fixed;
    top: 0;
    left: 0;
    right: 0;
    height: var(--navbar-height);
    background-color: var(--paper-light);
    border-bottom: 1px solid var(--border-soft);
    z-index: 1000;
    transition: box-shadow var(--transition-normal);
}

.navbar.scrolled {
    box-shadow: var(--shadow-md);
}

.navbar-container {
    display: flex;
    align-items: center;
    justify-content: space-between;
    height: 100%;
    max-width: var(--container-max);
    margin: 0 auto;
    padding: 0 var(--space-6);
    gap: var(--space-6);
}

/* Logo */
.logo {
    display: flex;
    align-items: center;
    gap: var(--space-2);
    flex-shrink: 0;
}

.logo-icon {
    font-size: 1.75rem;
}

.logo-text {
    font-family: var(--font-display);
    font-size: var(--text-xl);
    font-weight: 700;
    color: var(--ink-primary);
}

/* 导航链接 */
.nav-links {
    display: flex;
    align-items: center;
    gap: var(--space-1);
}

.nav-link {
    display: flex;
    align-items: center;
    gap: var(--space-1);
    padding: var(--space-2) var(--space-4);
    font-size: var(--text-base);
    font-weight: 500;
    color: var(--text-secondary);
    border-radius: var(--radius-md);
    transition: all var(--transition-fast);
}

.nav-link:hover,
.nav-link.active {
    color: var(--ink-primary);
    background-color: rgba(139, 69, 19, 0.05);
}

.dropdown-icon {
    width: 1rem;
    height: 1rem;
}

/* 下拉菜单 */
.nav-dropdown {
    position: relative;
}

.dropdown-menu {
    position: absolute;
    top: 100%;
    left: 0;
    min-width: 180px;
    padding: var(--space-2);
    background-color: var(--paper-light);
    border: 1px solid var(--border-soft);
    border-radius: var(--radius-lg);
    box-shadow: var(--shadow-lg);
    opacity: 0;
    visibility: hidden;
    transform: translateY(-10px);
    transition: all var(--transition-fast);
    z-index: 100;
}

.nav-dropdown:hover .dropdown-menu {
    opacity: 1;
    visibility: visible;
    transform: translateY(0);
}

.dropdown-item {
    display: block;
    padding: var(--space-2) var(--space-4);
    font-size: var(--text-sm);
    color: var(--text-secondary);
    border-radius: var(--radius-sm);
    transition: all var(--transition-fast);
}

.dropdown-item:hover {
    color: var(--ink-primary);
    background-color: rgba(139, 69, 19, 0.05);
}

/* 搜索框 */
.search-box {
    display: flex;
    align-items: center;
    flex: 1;
    max-width: 400px;
    height: 42px;
    padding: 0 var(--space-3);
    background-color: var(--paper-warm);
    border: 1px solid var(--border-soft);
    border-radius: var(--radius-full);
    transition: all var(--transition-fast);
}

.search-box:focus-within {
    border-color: var(--ink-primary);
    box-shadow: 0 0 0 3px rgba(139, 69, 19, 0.1);
}

.search-icon {
    width: 1.25rem;
    height: 1.25rem;
    color: var(--text-muted);
    flex-shrink: 0;
}

.search-input {
    flex: 1;
    border: none;
    background: none;
    padding: var(--space-2);
    outline: none;
    color: var(--text-primary);
}

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

.search-btn {
    padding: var(--space-2) var(--space-4);
    font-size: var(--text-sm);
    font-weight: 500;
    color: white;
    background-color: var(--ink-primary);
    border-radius: var(--radius-full);
    transition: all var(--transition-fast);
}

.search-btn:hover {
    background-color: var(--ink-secondary);
}

/* 用户区域 */
.user-area {
    position: relative;
}

.user-avatar {
    display: flex;
    align-items: center;
    justify-content: center;
    width: 40px;
    height: 40px;
    border-radius: 50%;
    overflow: hidden;
    border: 2px solid var(--border-soft);
    transition: all var(--transition-fast);
}

.user-avatar:hover {
    border-color: var(--ink-primary);
}

.user-avatar img {
    width: 100%;
    height: 100%;
    object-fit: cover;
}

.user-menu {
    position: absolute;
    top: 100%;
    right: 0;
    margin-top: var(--space-2);
    min-width: 200px;
    padding: var(--space-2);
    background-color: var(--paper-light);
    border: 1px solid var(--border-soft);
    border-radius: var(--radius-lg);
    box-shadow: var(--shadow-lg);
    opacity: 0;
    visibility: hidden;
    transform: translateY(-10px);
    transition: all var(--transition-fast);
    z-index: 100;
}

.user-area:hover .user-menu {
    opacity: 1;
    visibility: visible;
    transform: translateY(0);
}

.user-menu-item {
    display: flex;
    align-items: center;
    gap: var(--space-2);
    padding: var(--space-2) var(--space-3);
    font-size: var(--text-sm);
    color: var(--text-secondary);
    border-radius: var(--radius-sm);
    transition: all var(--transition-fast);
}

.user-menu-item:hover {
    color: var(--ink-primary);
    background-color: rgba(139, 69, 19, 0.05);
}

.user-menu-item.logout {
    color: var(--error-red);
}

.user-menu-divider {
    height: 1px;
    margin: var(--space-2) 0;
    background-color: var(--border-soft);
}

/* 移动端菜单按钮 */
.mobile-menu-btn {
    display: none;
    width: 40px;
    height: 40px;
    color: var(--text-primary);
}

.mobile-menu-btn svg {
    width: 24px;
    height: 24px;
}

/* 移动端菜单 */
.mobile-menu {
    display: none;
    position: absolute;
    top: 100%;
    left: 0;
    right: 0;
    padding: var(--space-4);
    background-color: var(--paper-light);
    border-bottom: 1px solid var(--border-soft);
    box-shadow: var(--shadow-lg);
}

.mobile-search {
    margin-bottom: var(--space-4);
}

.mobile-search input {
    width: 100%;
    padding: var(--space-3);
    border: 1px solid var(--border-soft);
    border-radius: var(--radius-md);
    background-color: var(--paper-warm);
}

.mobile-nav-link {
    display: block;
    padding: var(--space-3);
    font-size: var(--text-base);
    font-weight: 500;
    color: var(--text-secondary);
    border-bottom: 1px solid var(--border-soft);
}

.mobile-nav-link:last-child {
    border-bottom: none;
}

.mobile-nav-link.active {
    color: var(--ink-primary);
}

/* ========================================
   5. 轮播Banner
   ======================================== */
.hero-section {
    position: relative;
    padding: var(--space-12) 0;
    background: linear-gradient(135deg, var(--paper-light) 0%, var(--paper-warm) 100%);
}

.hero-container {
    position: relative;
    max-width: var(--container-max);
    margin: 0 auto;
    padding: 0 var(--space-6);
}

.hero-slider {
    position: relative;
    overflow: hidden;
    border-radius: var(--radius-xl);
}

.hero-slide {
    display: none;
    align-items: center;
    gap: var(--space-12);
    padding: var(--space-12);
    background: linear-gradient(135deg, rgba(139, 69, 19, 0.03) 0%, rgba(210, 105, 30, 0.05) 100%);
    border-radius: var(--radius-xl);
    min-height: 400px;
}

.hero-slide.active {
    display: flex;
    animation: fadeIn 0.5s ease;
}

@keyframes fadeIn {
    from { opacity: 0; transform: translateY(20px); }
    to { opacity: 1; transform: translateY(0); }
}

.hero-content {
    flex: 1;
}

.hero-badge {
    display: inline-block;
    padding: var(--space-1) var(--space-3);
    font-size: var(--text-xs);
    font-weight: 600;
    color: var(--ink-primary);
    background-color: rgba(139, 69, 19, 0.1);
    border-radius: var(--radius-full);
    margin-bottom: var(--space-4);
}

.hero-title {
    font-family: var(--font-display);
    font-size: var(--text-3xl);
    font-weight: 700;
    color: var(--text-primary);
    margin-bottom: var(--space-4);
    line-height: 1.3;
}

.hero-desc {
    font-size: var(--text-lg);
    color: var(--text-secondary);
    margin-bottom: var(--space-4);
    line-height: 1.8;
}

.hero-meta {
    display: flex;
    align-items: center;
    gap: var(--space-4);
    margin-bottom: var(--space-6);
    flex-wrap: wrap;
}

.hero-author {
    font-size: var(--text-sm);
    color: var(--text-muted);
}

.hero-tags {
    display: flex;
    gap: var(--space-2);
}

.tag {
    display: inline-block;
    padding: var(--space-1) var(--space-2);
    font-size: var(--text-xs);
    color: var(--ink-secondary);
    background-color: rgba(210, 105, 30, 0.1);
    border-radius: var(--radius-sm);
}

.hero-actions {
    display: flex;
    gap: var(--space-3);
    flex-wrap: wrap;
}

.hero-cover {
    flex-shrink: 0;
}

.hero-cover img {
    width: 220px;
    height: 300px;
    object-fit: cover;
    border-radius: var(--radius-lg);
    box-shadow: var(--shadow-xl);
}

/* 轮播控制 */
.slider-controls {
    display: flex;
    justify-content: center;
    gap: var(--space-2);
    margin-top: var(--space-6);
}

.slider-dot {
    width: 10px;
    height: 10px;
    border-radius: 50%;
    background-color: var(--border-soft);
    transition: all var(--transition-fast);
}

.slider-dot.active {
    width: 30px;
    border-radius: var(--radius-full);
    background-color: var(--ink-primary);
}

.slider-arrow {
    position: absolute;
    top: 50%;
    transform: translateY(-50%);
    width: 48px;
    height: 48px;
    display: flex;
    align-items: center;
    justify-content: center;
    background-color: var(--paper-light);
    border-radius: 50%;
    box-shadow: var(--shadow-md);
    color: var(--text-primary);
    transition: all var(--transition-fast);
    z-index: 10;
}

.slider-arrow:hover {
    background-color: var(--ink-primary);
    color: white;
}

.slider-arrow svg {
    width: 24px;
    height: 24px;
}

.slider-prev {
    left: var(--space-4);
}

.slider-next {
    right: var(--space-4);
}

/* ========================================
   6. 分类卡片
   ======================================== */
.categories-section {
    padding: var(--space-8) 0;
    background-color: var(--paper-light);
}

.categories-grid {
    display: grid;
    grid-template-columns: repeat(6, 1fr);
    gap: var(--space-4);
}

.category-card {
    display: flex;
    flex-direction: column;
    align-items: center;
    gap: var(--space-3);
    padding: var(--space-6);
    background-color: var(--paper-warm);
    border-radius: var(--radius-lg);
    border: 1px solid transparent;
    transition: all var(--transition-normal);
}

.category-card:hover {
    border-color: var(--ink-primary);
    transform: translateY(-4px);
    box-shadow: var(--shadow-hover);
}

.category-icon {
    font-size: 2rem;
}

.category-name {
    font-size: var(--text-sm);
    font-weight: 500;
    color: var(--text-secondary);
}

/* ========================================
   7. 通用区块
   ======================================== */
.section {
    padding: var(--space-16) 0;
}

.section-alt {
    background-color: var(--paper-light);
}

.section-header {
    display: flex;
    align-items: flex-end;
    justify-content: space-between;
    margin-bottom: var(--space-8);
}

.section-title-group {
    display: flex;
    flex-direction: column;
    gap: var(--space-1);
}

.section-title {
    font-family: var(--font-display);
    font-size: var(--text-2xl);
    font-weight: 700;
    color: var(--text-primary);
}

.section-subtitle {
    font-size: var(--text-sm);
    color: var(--text-muted);
}

.section-more {
    display: flex;
    align-items: center;
    gap: var(--space-1);
    font-size: var(--text-sm);
    font-weight: 500;
    color: var(--ink-primary);
    transition: all var(--transition-fast);
}

.section-more:hover {
    color: var(--ink-secondary);
}

.section-more svg {
    width: 1rem;
    height: 1rem;
}

/* ========================================
   8. 书籍网格
   ======================================== */
.books-grid {
    display: grid;
    grid-template-columns: repeat(auto-fill, minmax(180px, 1fr));
    gap: var(--space-6);
}

/* 书籍卡片 */
.book-card {
    position: relative;
    display: flex;
    flex-direction: column;
    background-color: var(--paper-light);
    border-radius: var(--radius-lg);
    overflow: hidden;
    border: 1px solid var(--border-soft);
    transition: all var(--transition-normal);
}

.book-card:hover {
    transform: translateY(-4px);
    box-shadow: var(--shadow-hover);
    border-color: var(--ink-primary);
}

.book-cover {
    position: relative;
    aspect-ratio: 3/4;
    overflow: hidden;
}

.book-cover img {
    width: 100%;
    height: 100%;
    object-fit: cover;
    transition: transform var(--transition-normal);
}

.book-card:hover .book-cover img {
    transform: scale(1.05);
}

.book-cover-placeholder {
    width: 100%;
    height: 100%;
    display: flex;
    align-items: center;
    justify-content: center;
    background: linear-gradient(135deg, var(--paper-warm) 0%, var(--border-soft) 100%);
    font-size: 3rem;
}

.book-badges {
    position: absolute;
    top: var(--space-2);
    left: var(--space-2);
    display: flex;
    flex-direction: column;
    gap: var(--space-1);
}

.book-badge {
    padding: var(--space-1) var(--space-2);
    font-size: var(--text-xs);
    font-weight: 600;
    color: white;
    background-color: var(--ink-primary);
    border-radius: var(--radius-sm);
}

.book-badge.update {
    background-color: var(--success-green);
}

.book-badge.new {
    background-color: var(--info-blue);
}

.book-info {
    padding: var(--space-4);
    display: flex;
    flex-direction: column;
    gap: var(--space-2);
}

.book-title {
    font-family: var(--font-display);
    font-size: var(--text-base);
    font-weight: 600;
    color: var(--text-primary);
    line-height: 1.4;
    display: -webkit-box;
    -webkit-line-clamp: 2;
    -webkit-box-orient: vertical;
    overflow: hidden;
}

.book-author {
    font-size: var(--text-sm);
    color: var(--text-muted);
}

.book-meta {
    display: flex;
    align-items: center;
    justify-content: space-between;
    font-size: var(--text-xs);
    color: var(--text-muted);
}

.book-rating {
    display: flex;
    align-items: center;
    gap: var(--space-1);
    color: var(--warning-amber);
}

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

/* ========================================
   9. 精选推荐
   ======================================== */
.featured-grid {
    display: grid;
    grid-template-columns: 2fr 1fr;
    gap: var(--space-6);
}

.featured-card {
    display: flex;
    border-radius: var(--radius-xl);
    overflow: hidden;
    background-color: var(--paper-light);
    border: 1px solid var(--border-soft);
    transition: all var(--transition-normal);
}

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

.featured-main {
    flex-direction: row;
}

.featured-main:hover {
    transform: translateY(-4px);
}

.featured-cover {
    position: relative;
    width: 280px;
    flex-shrink: 0;
}

.featured-cover img {
    width: 100%;
    height: 100%;
    object-fit: cover;
}

.featured-overlay {
    position: absolute;
    inset: 0;
    background: linear-gradient(to top, rgba(0,0,0,0.5) 0%, transparent 50%);
    display: flex;
    align-items: flex-start;
    padding: var(--space-4);
}

.featured-badge {
    padding: var(--space-1) var(--space-3);
    font-size: var(--text-xs);
    font-weight: 600;
    color: white;
    background-color: var(--ink-primary);
    border-radius: var(--radius-sm);
}

.featured-info {
    flex: 1;
    padding: var(--space-6);
    display: flex;
    flex-direction: column;
    justify-content: center;
    gap: var(--space-3);
}

.featured-title {
    font-family: var(--font-display);
    font-size: var(--text-2xl);
    font-weight: 700;
    color: var(--text-primary);
}

.featured-desc {
    font-size: var(--text-base);
    color: var(--text-secondary);
    line-height: 1.8;
    display: -webkit-box;
    -webkit-line-clamp: 3;
    -webkit-box-orient: vertical;
    overflow: hidden;
}

.featured-meta {
    display: flex;
    align-items: center;
    gap: var(--space-4);
    font-size: var(--text-sm);
    color: var(--text-muted);
}

.featured-rating {
    color: var(--warning-amber);
}

/* 侧边精选 */
.featured-secondary {
    display: grid;
    grid-template-columns: repeat(2, 1fr);
    gap: var(--space-4);
}

.featured-card-small {
    display: flex;
    flex-direction: column;
    background-color: var(--paper-light);
    border-radius: var(--radius-lg);
    overflow: hidden;
    border: 1px solid var(--border-soft);
    transition: all var(--transition-normal);
}

.featured-card-small:hover {
    transform: translateY(-2px);
    box-shadow: var(--shadow-md);
}

.featured-cover-small {
    aspect-ratio: 4/3;
    overflow: hidden;
}

.featured-cover-small img {
    width: 100%;
    height: 100%;
    object-fit: cover;
}

.featured-info-small {
    padding: var(--space-3);
}

.featured-info-small h4 {
    font-family: var(--font-display);
    font-size: var(--text-sm);
    font-weight: 600;
    color: var(--text-primary);
    margin-bottom: var(--space-1);
}

.featured-info-small .text-muted {
    font-size: var(--text-xs);
    color: var(--text-muted);
    margin-bottom: var(--space-2);
}

.tag-sm {
    font-size: var(--text-xs);
    padding: 2px 6px;
}

/* ========================================
   10. 书单卡片
   ======================================== */
.booklists-grid {
    display: grid;
    grid-template-columns: repeat(auto-fill, minmax(300px, 1fr));
    gap: var(--space-6);
}

.booklist-card {
    display: flex;
    flex-direction: column;
    background-color: var(--paper-warm);
    border-radius: var(--radius-lg);
    overflow: hidden;
    border: 1px solid var(--border-soft);
    transition: all var(--transition-normal);
}

.booklist-card:hover {
    transform: translateY(-4px);
    box-shadow: var(--shadow-hover);
}

.booklist-cover {
    aspect-ratio: 16/9;
    overflow: hidden;
}

.booklist-cover img {
    width: 100%;
    height: 100%;
    object-fit: cover;
    transition: transform var(--transition-normal);
}

.booklist-card:hover .booklist-cover img {
    transform: scale(1.05);
}

.booklist-info {
    padding: var(--space-5);
    display: flex;
    flex-direction: column;
    gap: var(--space-2);
}

.booklist-title {
    font-family: var(--font-display);
    font-size: var(--text-lg);
    font-weight: 600;
    color: var(--text-primary);
}

.booklist-desc {
    font-size: var(--text-sm);
    color: var(--text-secondary);
    line-height: 1.6;
}

.booklist-meta {
    display: flex;
    align-items: center;
    justify-content: space-between;
    font-size: var(--text-xs);
    color: var(--text-muted);
    margin-top: var(--space-2);
}

/* ========================================
   11. 数据统计
   ======================================== */
.stats-section {
    padding: var(--space-16) 0;
    background: linear-gradient(135deg, var(--ink-primary) 0%, var(--ink-secondary) 100%);
}

.stats-grid {
    display: grid;
    grid-template-columns: repeat(4, 1fr);
    gap: var(--space-8);
}

.stat-item {
    text-align: center;
    color: white;
}

.stat-icon {
    font-size: 2.5rem;
    margin-bottom: var(--space-3);
}

.stat-value {
    font-family: var(--font-display);
    font-size: var(--text-3xl);
    font-weight: 700;
    margin-bottom: var(--space-2);
}

.stat-label {
    font-size: var(--text-base);
    opacity: 0.9;
}

/* ========================================
   12. 页脚
   ======================================== */
.footer {
    padding: var(--space-16) 0 var(--space-8);
    background-color: var(--text-primary);
    color: var(--paper-warm);
}

.footer-grid {
    display: grid;
    grid-template-columns: 2fr repeat(3, 1fr);
    gap: var(--space-12);
    margin-bottom: var(--space-12);
}

.footer-logo {
    display: flex;
    align-items: center;
    gap: var(--space-2);
    margin-bottom: var(--space-4);
}

.footer-logo .logo-icon {
    font-size: 1.5rem;
}

.footer-logo .logo-text {
    font-family: var(--font-display);
    font-size: var(--text-xl);
    font-weight: 700;
    color: var(--paper-warm);
}

.footer-desc {
    font-size: var(--text-sm);
    color: var(--text-muted);
    line-height: 1.8;
    margin-bottom: var(--space-4);
}

.footer-social {
    display: flex;
    gap: var(--space-3);
}

.social-link {
    width: 40px;
    height: 40px;
    display: flex;
    align-items: center;
    justify-content: center;
    font-size: 1.25rem;
    background-color: rgba(255,255,255,0.1);
    border-radius: 50%;
    transition: all var(--transition-fast);
}

.social-link:hover {
    background-color: var(--ink-secondary);
    transform: translateY(-2px);
}

.footer-links h4 {
    font-family: var(--font-display);
    font-size: var(--text-base);
    font-weight: 600;
    margin-bottom: var(--space-4);
}

.footer-links ul {
    display: flex;
    flex-direction: column;
    gap: var(--space-3);
}

.footer-links a {
    font-size: var(--text-sm);
    color: var(--text-muted);
    transition: color var(--transition-fast);
}

.footer-links a:hover {
    color: var(--paper-warm);
}

.footer-bottom {
    padding-top: var(--space-8);
    border-top: 1px solid rgba(255,255,255,0.1);
    text-align: center;
    font-size: var(--text-sm);
    color: var(--text-muted);
}

.footer-bottom p:first-child {
    margin-bottom: var(--space-2);
}

/* ========================================
   13. 按钮
   ======================================== */
.btn {
    display: inline-flex;
    align-items: center;
    justify-content: center;
    gap: var(--space-2);
    font-family: var(--font-body);
    font-weight: 500;
    text-decoration: none;
    border: none;
    cursor: pointer;
    transition: all var(--transition-fast);
    user-select: none;
}

.btn:focus-visible {
    outline: 2px solid var(--ink-primary);
    outline-offset: 2px;
}

.btn:disabled {
    opacity: 0.6;
    cursor: not-allowed;
    pointer-events: none;
}

/* Primary */
.btn-primary {
    color: white;
    background-color: var(--ink-primary);
    padding: var(--space-3) var(--space-6);
    border-radius: var(--radius-md);
    font-size: var(--text-base);
}

.btn-primary:hover:not(:disabled) {
    background-color: var(--ink-secondary);
    transform: translateY(-1px);
    box-shadow: var(--shadow-md);
}

.btn-primary:active:not(:disabled) {
    transform: translateY(0);
}

/* Secondary */
.btn-secondary {
    color: var(--ink-primary);
    background-color: transparent;
    padding: var(--space-3) var(--space-6);
    border: 1px solid var(--ink-primary);
    border-radius: var(--radius-md);
    font-size: var(--text-base);
}

.btn-secondary:hover:not(:disabled) {
    color: white;
    background-color: var(--ink-primary);
}

/* Ghost */
.btn-ghost {
    color: var(--text-secondary);
    background-color: transparent;
    padding: var(--space-2) var(--space-4);
    border-radius: var(--radius-md);
}

.btn-ghost:hover {
    color: var(--ink-primary);
    background-color: rgba(139, 69, 19, 0.05);
}

/* Sizes */
.btn-sm {
    padding: var(--space-2) var(--space-4);
    font-size: var(--text-sm);
}

.btn-lg {
    padding: var(--space-4) var(--space-8);
    font-size: var(--text-lg);
}

.btn svg {
    width: 1.25rem;
    height: 1.25rem;
}

/* ========================================
   14. 回到顶部
   ======================================== */
.back-to-top {
    position: fixed;
    bottom: var(--space-8);
    right: var(--space-8);
    width: 48px;
    height: 48px;
    display: flex;
    align-items: center;
    justify-content: center;
    background-color: var(--ink-primary);
    color: white;
    border-radius: 50%;
    box-shadow: var(--shadow-lg);
    opacity: 0;
    visibility: hidden;
    transform: translateY(20px);
    transition: all var(--transition-normal);
    z-index: 999;
}

.back-to-top.visible {
    opacity: 1;
    visibility: visible;
    transform: translateY(0);
}

.back-to-top:hover {
    background-color: var(--ink-secondary);
    transform: translateY(-2px);
}

.back-to-top svg {
    width: 24px;
    height: 24px;
}

/* ========================================
   15. 响应式设计
   ======================================== */

/* 平板端 */
@media (max-width: 1024px) {
    .categories-grid {
        grid-template-columns: repeat(3, 1fr);
    }

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

    .featured-secondary {
        grid-template-columns: repeat(4, 1fr);
    }

    .stats-grid {
        grid-template-columns: repeat(2, 1fr);
        gap: var(--space-6);
    }

    .footer-grid {
        grid-template-columns: repeat(2, 1fr);
        gap: var(--space-8);
    }
}

/* 移动端 */
@media (max-width: 768px) {
    :root {
        --navbar-height: 60px;
    }

    .nav-links,
    .search-box,
    .user-area {
        display: none;
    }

    .mobile-menu-btn {
        display: flex;
    }

    .mobile-menu {
        display: block;
    }

    .hero-slide {
        flex-direction: column;
        padding: var(--space-6);
        text-align: center;
        min-height: auto;
    }

    .hero-cover {
        order: -1;
    }

    .hero-cover img {
        width: 160px;
        height: 220px;
    }

    .hero-title {
        font-size: var(--text-xl);
    }

    .hero-desc {
        font-size: var(--text-base);
    }

    .hero-meta {
        justify-content: center;
    }

    .hero-actions {
        justify-content: center;
    }

    .slider-arrow {
        display: none;
    }

    .categories-grid {
        grid-template-columns: repeat(2, 1fr);
        gap: var(--space-3);
    }

    .category-card {
        padding: var(--space-4);
    }

    .section-header {
        flex-direction: column;
        align-items: flex-start;
        gap: var(--space-3);
    }

    .books-grid {
        grid-template-columns: repeat(2, 1fr);
        gap: var(--space-4);
    }

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

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

    .stats-grid {
        grid-template-columns: repeat(2, 1fr);
        gap: var(--space-4);
    }

    .stat-value {
        font-size: var(--text-2xl);
    }

    .footer-grid {
        grid-template-columns: 1fr;
        gap: var(--space-8);
    }

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

    .footer-social {
        justify-content: center;
    }

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

    .back-to-top {
        bottom: var(--space-4);
        right: var(--space-4);
        width: 40px;
        height: 40px;
    }
}

/* 小屏手机 */
@media (max-width: 480px) {
    .container {
        padding: 0 var(--space-4);
    }

    .hero-section {
        padding: var(--space-8) 0;
    }

    .hero-cover img {
        width: 140px;
        height: 190px;
    }

    .books-grid {
        grid-template-columns: repeat(2, 1fr);
        gap: var(--space-3);
    }

    .book-info {
        padding: var(--space-3);
    }

    .book-title {
        font-size: var(--text-sm);
    }

    .featured-cover {
        width: 140px;
    }

    .featured-info {
        padding: var(--space-4);
    }

    .featured-title {
        font-size: var(--text-lg);
    }

    .featured-desc {
        font-size: var(--text-sm);
        -webkit-line-clamp: 2;
    }

    .btn-lg {
        padding: var(--space-3) var(--space-6);
        font-size: var(--text-base);
    }
}

/* ========================================
   16. 动画与过渡
   ======================================== */
@media (prefers-reduced-motion: reduce) {
    *,
    *::before,
    *::after {
        animation-duration: 0.01ms !important;
        animation-iteration-count: 1 !important;
        transition-duration: 0.01ms !important;
    }
}

/* 加载动画 */
.skeleton {
    background: linear-gradient(
        90deg,
        var(--border-soft) 25%,
        var(--paper-warm) 50%,
        var(--border-soft) 75%
    );
    background-size: 200% 100%;
    animation: skeleton-loading 1.5s infinite;
}

@keyframes skeleton-loading {
    0% { background-position: 200% 0; }
    100% { background-position: -200% 0; }
}

/* 滚动动画 */
.fade-in-up {
    opacity: 0;
    transform: translateY(30px);
    transition: all 0.6s ease;
}

.fade-in-up.visible {
    opacity: 1;
    transform: translateY(0);
}

/* ========================================
   17. 模态框
   ======================================== */
.modal {
    position: fixed;
    inset: 0;
    display: flex;
    align-items: center;
    justify-content: center;
    z-index: 1000;
    opacity: 0;
    visibility: hidden;
    transition: all var(--transition-normal);
}

.modal.active {
    opacity: 1;
    visibility: visible;
}

.modal-overlay {
    position: absolute;
    inset: 0;
    background-color: rgba(0, 0, 0, 0.5);
}

.modal-content {
    position: relative;
    background-color: var(--paper-light);
    border-radius: var(--radius-xl);
    box-shadow: var(--shadow-xl);
    max-width: 90vw;
    max-height: 90vh;
    overflow: auto;
    transform: scale(0.9);
    transition: transform var(--transition-normal);
}

.modal.active .modal-content {
    transform: scale(1);
}

.modal-close {
    position: absolute;
    top: var(--space-4);
    right: var(--space-4);
    width: 32px;
    height: 32px;
    display: flex;
    align-items: center;
    justify-content: center;
    font-size: 1.5rem;
    color: var(--text-muted);
    background: none;
    border: none;
    cursor: pointer;
    transition: color var(--transition-fast);
    z-index: 1;
}

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

.modal-title {
    font-family: var(--font-display);
    font-size: var(--text-xl);
    font-weight: 600;
    color: var(--text-primary);
    text-align: center;
    margin-bottom: var(--space-6);
    padding-top: var(--space-6);
}

/* 认证模态框 */
.auth-modal-content {
    width: 400px;
    padding: var(--space-8);
}

.auth-form {
    display: flex;
    flex-direction: column;
    gap: var(--space-4);
}

.auth-form .form-group {
    display: flex;
    flex-direction: column;
    gap: var(--space-2);
}

.auth-form label {
    font-size: var(--text-sm);
    font-weight: 500;
    color: var(--text-primary);
}

.auth-form input,
.auth-form textarea {
    padding: var(--space-3) var(--space-4);
    font-size: var(--text-base);
    color: var(--text-primary);
    background-color: var(--paper-warm);
    border: 1px solid var(--border-soft);
    border-radius: var(--radius-md);
    transition: all var(--transition-fast);
}

.auth-form input:focus,
.auth-form textarea:focus {
    outline: none;
    border-color: var(--ink-primary);
    box-shadow: 0 0 0 3px rgba(139, 69, 19, 0.1);
}

.btn-block {
    width: 100%;
    margin-top: var(--space-2);
}

.auth-msg {
    font-size: var(--text-sm);
    text-align: center;
    min-height: 20px;
}

.auth-switch {
    text-align: center;
    margin-top: var(--space-4);
    font-size: var(--text-sm);
    color: var(--text-muted);
}

.auth-switch a {
    color: var(--ink-primary);
    text-decoration: none;
    font-weight: 500;
}

.auth-switch a:hover {
    text-decoration: underline;
}

.auth-btn {
    margin-left: var(--space-2);
}

/* 用户下拉菜单 */
.user-dropdown {
    position: relative;
}

.user-dropdown .user-btn {
    display: flex;
    align-items: center;
    gap: var(--space-2);
    padding: var(--space-2) var(--space-3);
    background: none;
    border: 1px solid var(--border-soft);
    border-radius: var(--radius-full);
    cursor: pointer;
    transition: all var(--transition-fast);
}

.user-dropdown .user-btn:hover {
    background-color: var(--paper-warm);
}

.user-dropdown .user-avatar {
    width: 28px;
    height: 28px;
    font-size: 1rem;
}

.user-dropdown .user-name {
    font-size: var(--text-sm);
    color: var(--text-primary);
}

.user-dropdown .user-menu {
    position: absolute;
    top: 100%;
    right: 0;
    margin-top: var(--space-2);
    min-width: 160px;
    background-color: var(--paper-light);
    border: 1px solid var(--border-soft);
    border-radius: var(--radius-lg);
    box-shadow: var(--shadow-lg);
    opacity: 0;
    visibility: hidden;
    transform: translateY(-10px);
    transition: all var(--transition-fast);
    z-index: 100;
}

.user-dropdown:hover .user-menu {
    opacity: 1;
    visibility: visible;
    transform: translateY(0);
}

.user-menu-item {
    display: flex;
    align-items: center;
    gap: var(--space-2);
    padding: var(--space-3) var(--space-4);
    font-size: var(--text-sm);
    color: var(--text-secondary);
    text-decoration: none;
    transition: all var(--transition-fast);
}

.user-menu-item:hover {
    background-color: var(--paper-warm);
    color: var(--text-primary);
}

.user-menu-divider {
    height: 1px;
    background-color: var(--border-soft);
    margin: var(--space-2) 0;
}

.user-menu-item.logout {
    color: var(--error-red);
}