/**
 * 主样式文件
 * 
 * 包含全局样式、组件样式、页面样式
 */

/* ==========================================================================
   CSS 变量（主题配置）
   ========================================================================== */

:root {
    /* 主色调 */
    --color-primary: #111827;
    --color-primary-hover: #2f3a4d;
    --color-primary-light: #edf5ff;
    
    /* 辅助色 */
    --color-success: #27ae60;
    --color-warning: #f39c12;
    --color-error: #e74c3c;
    
    /* 中性色 */
    --color-white: #ffffff;
    --color-black: #000000;
    --color-gray-50: #f9fafb;
    --color-gray-100: #f3f4f6;
    --color-gray-200: #e5e7eb;
    --color-gray-300: #d1d5db;
    --color-gray-400: #9ca3af;
    --color-gray-500: #6b7280;
    --color-gray-600: #4b5563;
    --color-gray-700: #374151;
    --color-gray-800: #1f2937;
    --color-gray-900: #111827;
    
    /* 背景色 */
    --bg-primary: var(--color-white);
    --bg-secondary: var(--color-gray-50);
    --bg-tertiary: var(--color-gray-100);
    
    /* 文字色 */
    --text-primary: var(--color-gray-900);
    --text-secondary: var(--color-gray-600);
    --text-muted: var(--color-gray-400);
    
    /* 边框色 */
    --border-color: var(--color-gray-200);
    
    /* 阴影 */
    --shadow-sm: 0 1px 2px 0 rgba(0, 0, 0, 0.05);
    --shadow-md: 0 4px 6px -1px rgba(0, 0, 0, 0.1);
    --shadow-lg: 0 10px 15px -3px rgba(0, 0, 0, 0.1);
    
    /* 间距 */
    --spacing-xs: 0.25rem;
    --spacing-sm: 0.5rem;
    --spacing-md: 1rem;
    --spacing-lg: 1.5rem;
    --spacing-xl: 2rem;
    --spacing-2xl: 3rem;
    
    /* 圆角 */
    --radius-sm: 0.25rem;
    --radius-md: 0.5rem;
    --radius-lg: 0.75rem;
    --radius-full: 9999px;
    
    /* 字体 */
    --font-family: -apple-system, BlinkMacSystemFont, "Segoe UI", Roboto, "Helvetica Neue", Arial, sans-serif;
    --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;
}

/* ==========================================================================
   基础样式重置
   ========================================================================== */

*, *::before, *::after {
    box-sizing: border-box;
    margin: 0;
    padding: 0;
}

html {
    font-size: 16px;
    line-height: 1.5;
}

body {
    font-family: var(--font-family);
    color: var(--text-primary);
    background-color: var(--bg-secondary);
    min-height: 100vh;
    display: flex;
    flex-direction: column;
}

a {
    color: var(--color-primary);
    text-decoration: none;
    transition: color 0.2s ease;
}

a:hover {
    color: var(--color-primary-hover);
}

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

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

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

/* ==========================================================================
   通用容器
   ========================================================================== */

.container {
    max-width: 1200px;
    margin: 0 auto;
    padding: 0 var(--spacing-md);
}

/* ==========================================================================
   导航栏
   ========================================================================== */

.navbar {
    display: flex;
    justify-content: space-between;
    align-items: center;
    padding: var(--spacing-md) 0;
    background-color: var(--bg-primary);
    border-bottom: 1px solid var(--border-color);
    box-shadow: var(--shadow-sm);
    position: sticky;
    top: 0;
    z-index: 100;
}

.navbar-container {
    display: flex;
    justify-content: space-between;
    align-items: center;
    width: 100%;
    max-width: 1200px;
    margin: 0 auto;
    padding: 0 var(--spacing-md);
}

.nav-search {
    display: flex;
    align-items: center;
    flex: 1;
    justify-content: center;
}

.english-lesson-page {
    background: #f7fafc;
}

.english-lesson-shell {
    width: min(100%, 960px);
    margin: 0 auto;
    padding: 20px 14px 36px;
}

.english-lesson-header {
    display: grid;
    gap: 12px;
    margin-bottom: 18px;
}

.english-lesson-brand {
    display: inline-flex;
    align-items: center;
    gap: 10px;
    color: var(--text-secondary);
    font-size: var(--font-size-sm);
    text-decoration: none;
}

.english-lesson-brand img {
    width: 32px;
    height: 32px;
}

.english-lesson-header h1 {
    color: var(--text-primary);
    font-size: var(--font-size-2xl);
    line-height: 1.25;
}

.english-lesson-grid {
    display: grid;
    grid-template-columns: repeat(auto-fit, minmax(150px, 1fr));
    gap: 14px;
    align-items: start;
}

.english-lesson-tile {
    position: relative;
    display: block;
    width: 100%;
    min-height: 120px;
    padding: 0;
    overflow: hidden;
    border: 1px solid var(--border-color);
    border-radius: var(--radius-md);
    background: var(--bg-primary);
    box-shadow: var(--shadow-sm);
    cursor: pointer;
}

.english-lesson-tile:focus-visible {
    outline: 3px solid var(--color-primary-light);
    outline-offset: 3px;
}

.english-lesson-tile img {
    width: 100%;
    height: auto;
    display: block;
}

.english-lesson-play-indicator {
    position: absolute;
    right: 10px;
    bottom: 10px;
    padding: 5px 8px;
    border-radius: var(--radius-sm);
    background: rgba(17, 24, 39, 0.78);
    color: #fff;
    font-size: 12px;
}

.english-lesson-tile.is-loading .english-lesson-play-indicator {
    background: #f39c12;
}

.english-lesson-tile.is-playing {
    border-color: var(--color-success);
    box-shadow: 0 0 0 3px rgba(39, 174, 96, 0.18);
}

.english-lesson-tile.is-playing .english-lesson-play-indicator {
    background: var(--color-success);
}

.english-lesson-status {
    min-height: 24px;
    margin-top: 14px;
    color: var(--text-secondary);
    font-size: var(--font-size-sm);
}

.learning-actions {
    width: min(100%, 1400px);
    margin: var(--spacing-lg) auto 0;
    padding: 0 var(--spacing-xl);
}

.catalog-main {
    width: min(100%, 1120px);
    margin: 0 auto;
    padding: var(--spacing-xl);
}

.catalog-header {
    display: grid;
    gap: var(--spacing-md);
    margin-bottom: var(--spacing-lg);
}

.catalog-header h1 {
    font-size: var(--font-size-2xl);
    color: var(--text-primary);
}

.catalog-filter {
    display: flex;
    gap: var(--spacing-sm);
    flex-wrap: wrap;
}

.catalog-filter input,
.catalog-filter select {
    min-height: 40px;
    padding: var(--spacing-sm) var(--spacing-md);
    border: 1px solid var(--border-color);
    border-radius: var(--radius-md);
    background: var(--bg-primary);
}

.lesson-grid {
    display: grid;
    grid-template-columns: repeat(auto-fill, minmax(220px, 1fr));
    gap: var(--spacing-md);
}

.lesson-card {
    display: grid;
    gap: var(--spacing-sm);
    padding: var(--spacing-lg);
    background: var(--bg-primary);
    border: 1px solid var(--border-color);
    border-radius: var(--radius-md);
    box-shadow: var(--shadow-sm);
}

.lesson-card h3 {
    font-size: var(--font-size-lg);
    color: var(--text-primary);
}

.lesson-card p {
    color: var(--text-secondary);
    font-size: var(--font-size-sm);
}

@media (max-width: 520px) {
    .english-lesson-grid {
        grid-template-columns: 1fr;
    }
}

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

.search-input {
    padding: var(--spacing-sm) var(--spacing-md);
    border: 1px solid var(--border-color);
    border-radius: var(--radius-md);
    font-size: var(--font-size-sm);
    width: 250px;
    transition: border-color 0.2s ease, box-shadow 0.2s ease;
}

.search-input:focus {
    outline: none;
    border-color: var(--color-primary);
    box-shadow: 0 0 0 3px var(--color-primary-light);
}

.search-btn {
    background-color: var(--color-primary);
    color: white;
    padding: var(--spacing-sm) var(--spacing-md);
    border-radius: var(--radius-md);
    cursor: pointer;
    transition: background-color 0.2s ease;
    font-size: var(--font-size-base);
}

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

.nav-user {
    display: flex;
    align-items: center;
    gap: var(--spacing-md);
}

.nav-user .username {
    color: var(--text-secondary);
    font-size: var(--font-size-sm);
    font-weight: 500;
}

.nav-link {
    color: var(--color-primary);
    font-size: var(--font-size-sm);
    font-weight: 500;
    padding: var(--spacing-sm) var(--spacing-md);
    border-radius: var(--radius-md);
    transition: background-color 0.2s ease;
}

.nav-link:hover {
    background-color: var(--color-primary-light);
    color: var(--color-primary-hover);
}

.admin-link {
    background-color: var(--color-primary-light);
}

.nav-brand {
    color: var(--text-primary);
    font-size: var(--font-size-lg);
    font-weight: 700;
    display: inline-flex;
    align-items: center;
    gap: var(--spacing-sm);
    flex-shrink: 0;
}

.brand-logo {
    width: 40px;
    height: 40px;
    object-fit: contain;
}

/* ==========================================================================
   页脚
   ========================================================================== */

.footer {
    background-color: var(--bg-primary);
    border-top: 1px solid var(--border-color);
    padding: var(--spacing-lg) 0;
    text-align: center;
    color: var(--text-muted);
    font-size: var(--font-size-sm);
    margin-top: auto;
}

.footer-container {
    max-width: 1200px;
    margin: 0 auto;
    padding: 0 var(--spacing-md);
}

.copyright {
    display: flex;
    align-items: center;
    justify-content: center;
    gap: var(--spacing-md);
    flex-wrap: wrap;
}

.divider {
    color: var(--border-color);
}

.footer-record-link {
    color: var(--color-primary);
    transition: color 0.2s ease;
}

.footer-record-link:hover {
    color: var(--color-primary-hover);
}

.public-security-record {
    display: inline-flex;
    align-items: center;
    gap: 4px;
}

.public-security-icon {
    width: 16px;
    height: 16px;
    object-fit: contain;
}

/* ==========================================================================
   按钮样式
   ========================================================================== */

.btn {
    display: inline-block;
    padding: var(--spacing-sm) var(--spacing-md);
    font-size: var(--font-size-sm);
    font-weight: 500;
    text-align: center;
    border-radius: var(--radius-md);
    transition: all 0.2s ease;
    cursor: pointer;
    border: 1px solid transparent;
}

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

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

.btn-secondary {
    background-color: var(--color-gray-200);
    color: var(--color-gray-700);
}

.btn-secondary:hover {
    background-color: var(--color-gray-300);
}

.btn-logout {
    background-color: transparent;
    color: var(--color-gray-600);
    border: 1px solid var(--border-color);
}

.btn-logout:hover {
    background-color: var(--color-gray-100);
    color: var(--color-gray-800);
}

.btn-block {
    display: block;
    width: 100%;
}

/* ==========================================================================
   表单样式
   ========================================================================== */

.form-group {
    margin-bottom: var(--spacing-md);
}

.form-group label {
    display: block;
    margin-bottom: var(--spacing-xs);
    font-size: var(--font-size-sm);
    font-weight: 500;
    color: var(--text-secondary);
}

.form-group input,
.form-group textarea,
.form-group select {
    width: 100%;
    padding: var(--spacing-sm) var(--spacing-md);
    border: 1px solid var(--border-color);
    border-radius: var(--radius-md);
    font-size: var(--font-size-base);
    transition: border-color 0.2s ease, box-shadow 0.2s ease;
}

.form-group input:focus,
.form-group textarea:focus,
.form-group select:focus {
    outline: none;
    border-color: var(--color-primary);
    box-shadow: 0 0 0 3px var(--color-primary-light);
}

.form-options {
    display: flex;
    justify-content: space-between;
    align-items: center;
}

.checkbox-label {
    display: flex;
    align-items: center;
    gap: var(--spacing-xs);
    font-size: var(--font-size-sm);
    color: var(--text-secondary);
    cursor: pointer;
}

.forgot-link {
    font-size: var(--font-size-sm);
    color: var(--color-primary);
}

/* ==========================================================================
   警告框/提示框
   ========================================================================== */

.alert {
    padding: var(--spacing-md);
    border-radius: var(--radius-md);
    margin-bottom: var(--spacing-md);
    font-size: var(--font-size-sm);
}

.alert-success {
    background-color: #d4edda;
    color: #155724;
    border: 1px solid #c3e6cb;
}

.alert-error {
    background-color: #f8d7da;
    color: #721c24;
    border: 1px solid #f5c6cb;
}

.alert-warning {
    background-color: #fff3cd;
    color: #856404;
    border: 1px solid #ffeaa7;
}

/* ==========================================================================
   登录页面
   ========================================================================== */

.login-page {
    display: flex;
    align-items: center;
    justify-content: center;
    min-height: 100vh;
    background: linear-gradient(135deg, var(--color-primary-light) 0%, var(--color-white) 100%);
}

.login-container {
    width: 100%;
    max-width: 400px;
    padding: var(--spacing-md);
}

.login-box {
    background-color: var(--bg-primary);
    border-radius: var(--radius-lg);
    box-shadow: var(--shadow-lg);
    padding: var(--spacing-2xl);
}

.login-header {
    text-align: center;
    margin-bottom: var(--spacing-xl);
}

.login-header h1 {
    font-size: var(--font-size-2xl);
    color: var(--color-primary);
    margin-bottom: var(--spacing-xs);
}

.login-header p {
    color: var(--text-muted);
    font-size: var(--font-size-base);
}

.login-form {
    margin-bottom: var(--spacing-md);
}

.login-footer {
    text-align: center;
    font-size: var(--font-size-sm);
    color: var(--text-secondary);
    padding-top: var(--spacing-md);
    border-top: 1px solid var(--border-color);
}

/* ==========================================================================
   主内容区
   ========================================================================== */

.main-content {
    padding: var(--spacing-xl) 0;
    align-items: flex-start;
    flex: 1;
    width: 100%;
}

.main-content h2 {
    font-size: var(--font-size-2xl);
    margin-bottom: var(--spacing-lg);
    color: var(--text-primary);
}

.guest-home {
    background: #f6f8fb;
}

.guest-main {
    flex: 1;
    width: 100%;
}

.guest-hero {
    display: grid;
    grid-template-columns: minmax(0, 0.95fr) minmax(320px, 1.05fr);
    gap: var(--spacing-2xl);
    align-items: center;
    max-width: 1200px;
    min-height: calc(100vh - 160px);
    margin: 0 auto;
    padding: clamp(40px, 7vw, 88px) var(--spacing-md);
}

.guest-logo {
    width: 88px;
    height: 88px;
    object-fit: contain;
    margin-bottom: var(--spacing-lg);
}

.guest-kicker {
    color: var(--color-primary);
    font-size: var(--font-size-sm);
    font-weight: 700;
    margin-bottom: var(--spacing-md);
}

.guest-hero h1 {
    color: var(--text-primary);
    font-size: 3rem;
    line-height: 1.12;
    margin-bottom: var(--spacing-md);
}

.guest-lead {
    color: var(--text-secondary);
    font-size: var(--font-size-lg);
    line-height: 1.8;
    max-width: 560px;
}

.guest-actions {
    display: flex;
    flex-wrap: wrap;
    gap: var(--spacing-md);
    margin-top: var(--spacing-xl);
}

.guest-carousel {
    position: relative;
    min-height: 380px;
    border-radius: var(--radius-lg);
    overflow: hidden;
    background:
        linear-gradient(145deg, rgba(17, 24, 39, 0.94), rgba(17, 24, 39, 0.72)),
        radial-gradient(circle at top right, rgba(39, 174, 96, 0.34), transparent 42%),
        #18212f;
    box-shadow: var(--shadow-lg);
}

.guest-slides {
    position: relative;
    min-height: 380px;
}

.guest-slide {
    position: absolute;
    inset: 0;
    display: flex;
    flex-direction: column;
    justify-content: flex-end;
    gap: var(--spacing-sm);
    padding: var(--spacing-2xl);
    color: var(--color-white);
    opacity: 0;
    transform: translateX(16px);
    transition: opacity 0.35s ease, transform 0.35s ease;
}

.guest-slide.is-active {
    opacity: 1;
    transform: translateX(0);
}

.guest-slide span {
    font-size: var(--font-size-sm);
    font-weight: 700;
}

.guest-slide h2 {
    max-width: 560px;
    font-size: var(--font-size-2xl);
    line-height: 1.25;
}

.guest-slide p {
    max-width: 560px;
    font-size: var(--font-size-base);
    line-height: 1.8;
}

.guest-carousel-controls {
    position: absolute;
    left: var(--spacing-2xl);
    bottom: var(--spacing-lg);
    display: flex;
    gap: var(--spacing-sm);
}

.guest-carousel-controls button {
    width: 34px;
    height: 4px;
    border-radius: var(--radius-full);
    background: rgba(255, 255, 255, 0.45);
}

.guest-carousel-controls button.is-active {
    background: var(--color-white);
}

.guest-overview {
    display: grid;
    grid-template-columns: repeat(3, minmax(0, 1fr));
    gap: var(--spacing-lg);
    max-width: 1200px;
    margin: 0 auto;
    padding: 0 var(--spacing-md) var(--spacing-2xl);
}

.guest-overview div {
    background: var(--bg-primary);
    border: 1px solid var(--border-color);
    border-radius: var(--radius-md);
    padding: var(--spacing-lg);
    box-shadow: var(--shadow-sm);
}

.guest-overview h2 {
    color: var(--text-primary);
    font-size: var(--font-size-lg);
    margin-bottom: var(--spacing-sm);
}

.guest-overview p {
    color: var(--text-secondary);
    line-height: 1.7;
}

/* ==========================================================================
   视频网格布局
   ========================================================================== */

.video-grid {
    display: grid;
    grid-template-columns: repeat(auto-fill, minmax(280px, 1fr));
    gap: var(--spacing-lg);
    align-content: start;
    align-items: start;
    flex: 1;
    min-width: 0;
}

.video-card {
    background-color: var(--bg-primary);
    border-radius: var(--radius-lg);
    overflow: hidden;
    box-shadow: var(--shadow-md);
    transition: transform 0.2s ease, box-shadow 0.2s ease;
    cursor: pointer;
    align-self: start;
    height: fit-content;
    max-width: 450px;
}

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

.video-thumbnail {
    position: relative;
    width: 100%;
    padding-top: 56.25%; /* 16:9 比例 */
    background-color: var(--color-gray-200);
    overflow: hidden;
    background-image: linear-gradient(135deg, #e8e8e8 25%, transparent 25%),
                      linear-gradient(225deg, #e8e8e8 25%, transparent 25%),
                      linear-gradient(315deg, #e8e8e8 25%, transparent 25%),
                      linear-gradient(45deg, #e8e8e8 25%, transparent 25%);
}

.video-thumbnail img {
    position: absolute;
    top: 0;
    left: 0;
    width: 100%;
    height: 100%;
    object-fit: cover;
}

.placeholder-thumbnail {
    position: absolute;
    top: 0;
    left: 0;
    width: 100%;
    height: 100%;
    display: flex;
    align-items: center;
    justify-content: center;
    color: var(--text-muted);
    font-size: var(--font-size-lg);
    background-color: var(--color-gray-200);
}

.video-info {
    padding: var(--spacing-md);
}

.video-title {
    font-size: var(--font-size-base);
    font-weight: 600;
    color: var(--text-primary);
    margin-bottom: var(--spacing-xs);
    overflow: hidden;
    text-overflow: ellipsis;
    white-space: nowrap;
}

.video-description {
    font-size: var(--font-size-sm);
    color: var(--text-secondary);
    overflow: hidden;
    text-overflow: ellipsis;
    display: -webkit-box;
    -webkit-line-clamp: 2;
    -webkit-box-orient: vertical;
}

.empty-message {
    text-align: center;
    color: var(--text-muted);
    padding: var(--spacing-2xl);
    grid-column: 1 / -1;
}

/* ==========================================================================
   视频播放页
   ========================================================================== */

.video-page {
    max-width: 900px;
    margin: 0 auto;
}

.video-player-container {
    background-color: var(--bg-primary);
    border-radius: var(--radius-lg);
    overflow: hidden;
    box-shadow: var(--shadow-lg);
}

.video-player {
    background-color: var(--color-black);
    width: 100%;
}

.video-element {
    width: 100%;
    height: auto;
    max-height: 500px;
    display: block;
}

.video-info-section {
    padding: var(--spacing-lg);
}

.video-info-section .video-title {
    font-size: var(--font-size-2xl);
    margin-bottom: var(--spacing-sm);
}

.video-info-section .video-description {
    color: var(--text-secondary);
    margin-bottom: var(--spacing-md);
}

.video-meta {
    display: flex;
    gap: var(--spacing-lg);
    color: var(--text-muted);
    font-size: var(--font-size-sm);
}

/* ==========================================================================
   消息提示组件（模态框）
   ========================================================================== */

.modal-overlay {
    position: fixed;
    top: 0;
    left: 0;
    right: 0;
    bottom: 0;
    background: rgba(0, 0, 0, 0.5);
    display: flex;
    align-items: center;
    justify-content: center;
    z-index: 1000;
    opacity: 0;
    transition: opacity 0.3s ease;
}

.modal-overlay.show {
    opacity: 1;
}

.modal {
    background: var(--bg-primary);
    border-radius: var(--radius-lg);
    padding: var(--spacing-xl);
    max-width: 400px;
    width: 90%;
    text-align: center;
    transform: scale(0.9);
    transition: transform 0.3s ease;
    box-shadow: var(--shadow-lg);
}

.modal-overlay.show .modal {
    transform: scale(1);
}

.modal-icon {
    font-size: 3rem;
    margin-bottom: var(--spacing-md);
    line-height: 1;
}

.modal-success .modal-icon {
    color: var(--color-success);
}

.modal-error .modal-icon {
    color: var(--color-error);
}

.modal-warning .modal-icon {
    color: var(--color-warning);
}

.modal-title {
    font-size: var(--font-size-xl);
    font-weight: 600;
    color: var(--text-primary);
    margin-bottom: var(--spacing-sm);
}

.modal-message {
    font-size: var(--font-size-base);
    color: var(--text-secondary);
    margin-bottom: var(--spacing-lg);
    line-height: 1.6;
}

.modal-actions {
    display: flex;
    gap: var(--spacing-md);
    justify-content: center;
}

.modal-actions .btn {
    min-width: 80px;
}

/* ==========================================================================
   响应式设计
   ========================================================================== */

/* 平板端：768px - 1023px */
@media (max-width: 1023px) {
    .search-input {
        width: 200px;
    }
}

/* 移动端：≤ 767px */
@media (max-width: 767px) {
    .navbar-container {
        flex-direction: column;
        gap: var(--spacing-md);
    }
    
    .nav-search {
        width: 100%;
        justify-content: stretch;
    }
    
    .search-form {
        width: 100%;
    }
    
    .search-input {
        width: 100%;
        flex: 1;
    }
    
    .nav-user {
        width: 100%;
        justify-content: center;
        flex-wrap: wrap;
    }

    .nav-brand {
        justify-content: center;
    }
    
    .video-grid {
        grid-template-columns: 1fr;
        gap: var(--spacing-md);
    }

    .guest-hero {
        grid-template-columns: 1fr;
        min-height: auto;
        padding-top: var(--spacing-2xl);
    }

    .guest-hero h1 {
        font-size: 2.2rem;
    }

    .guest-carousel,
    .guest-slides {
        min-height: 320px;
    }

    .guest-slide {
        padding: var(--spacing-xl);
    }

    .guest-carousel-controls {
        left: var(--spacing-xl);
    }

    .guest-overview {
        grid-template-columns: 1fr;
    }
    
    .login-page {
        flex-direction: column;
    }
    
    .login-box {
        padding: var(--spacing-lg);
    }
    
    .modal {
        padding: var(--spacing-lg);
    }
    
    .modal-actions {
        flex-direction: column;
    }
    
    .modal-actions .btn {
        width: 100%;
    }
}