/* ========================================
   中小学人工智能通识学习平台 - 公共样式
   参考风格：ai.myuclass.com
   ======================================== */

/* CSS变量 */
:root {
    --primary: #3b82f6;
    --primary-dark: #2563eb;
    --primary-light: #93c5fd;
    --primary-bg: #eff6ff;
    --secondary: #8b5cf6;
    --secondary-dark: #7c3aed;
    --success: #22c55e;
    --warning: #f59e0b;
    --danger: #ef4444;
    --text-primary: #1f2937;
    --text-secondary: #6b7280;
    --text-light: #9ca3af;
    --bg-primary: #ffffff;
    --bg-secondary: #f8fafc;
    --bg-tertiary: #f1f5f9;
    --border-color: #e5e7eb;
    --border-light: #f3f4f6;
    --shadow-sm: 0 1px 2px rgba(0,0,0,0.05);
    --shadow-md: 0 4px 6px -1px rgba(0,0,0,0.1), 0 2px 4px -2px rgba(0,0,0,0.1);
    --shadow-lg: 0 10px 15px -3px rgba(0,0,0,0.1), 0 4px 6px -4px rgba(0,0,0,0.1);
    --shadow-xl: 0 20px 25px -5px rgba(0,0,0,0.1), 0 8px 10px -6px rgba(0,0,0,0.1);
    --radius-sm: 6px;
    --radius-md: 10px;
    --radius-lg: 16px;
    --radius-xl: 24px;
    --transition: all 0.3s ease;
}

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

html {
    scroll-behavior: smooth;
    font-size: 16px;
}

body {
    font-family: -apple-system, BlinkMacSystemFont, 'PingFang SC', 'Microsoft YaHei', 'Helvetica Neue', Arial, sans-serif;
    color: var(--text-primary);
    background: var(--bg-secondary);
    line-height: 1.6;
    -webkit-font-smoothing: antialiased;
}

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

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

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

/* 容器 */
.container {
    max-width: 1200px;
    margin: 0 auto;
    padding: 0 20px;
}

/* ========================================
   头部导航
   ======================================== */
.site-header {
    background: var(--bg-primary);
    border-bottom: 1px solid var(--border-color);
    position: sticky;
    top: 0;
    z-index: 1000;
    box-shadow: var(--shadow-sm);
}

.header-inner {
    display: flex;
    align-items: center;
    justify-content: space-between;
    height: 64px;
}

.logo {
    display: flex;
    align-items: center;
    gap: 8px;
    font-size: 20px;
    font-weight: 700;
    color: var(--primary);
    text-decoration: none;
}

.logo-icon {
    font-size: 28px;
}

.logo-img {
    height: 36px;
    width: auto;
    border-radius: 4px;
    object-fit: contain;
}

.logo-text {
    background: linear-gradient(135deg, var(--primary), var(--secondary));
    -webkit-background-clip: text;
    -webkit-text-fill-color: transparent;
    background-clip: text;
}

.logo-text-short {
    display: none;
    background: linear-gradient(135deg, var(--primary), var(--secondary));
    -webkit-background-clip: text;
    -webkit-text-fill-color: transparent;
    background-clip: text;
    font-size: 16px;
    font-weight: 700;
    white-space: nowrap;
}

.main-nav {
    display: flex;
    gap: 8px;
}

.nav-link {
    padding: 8px 16px;
    border-radius: var(--radius-sm);
    color: var(--text-secondary);
    font-size: 15px;
    font-weight: 500;
    transition: var(--transition);
}

.nav-link:hover,
.nav-link.active {
    color: var(--primary);
    background: var(--primary-bg);
}

.header-right {
    display: flex;
    align-items: center;
    gap: 12px;
}

.user-info {
    position: relative;
    display: flex;
    align-items: center;
    gap: 8px;
    cursor: pointer;
    padding: 6px 12px;
    border-radius: var(--radius-sm);
    transition: var(--transition);
}

.user-info:hover {
    background: var(--bg-tertiary);
}

.user-name {
    font-size: 14px;
    color: var(--text-primary);
    font-weight: 500;
}

.vip-badge {
    background: linear-gradient(135deg, #f59e0b, #ef4444);
    color: #fff;
    font-size: 11px;
    padding: 2px 6px;
    border-radius: 4px;
    font-weight: 700;
}

.power-badge {
    font-size: 13px;
    color: var(--warning);
    font-weight: 600;
}

.user-dropdown {
    display: none;
    position: absolute;
    top: 100%;
    right: 0;
    background: var(--bg-primary);
    border: 1px solid var(--border-color);
    border-radius: var(--radius-md);
    box-shadow: var(--shadow-lg);
    min-width: 140px;
    z-index: 100;
    overflow: hidden;
}

.user-info:hover .user-dropdown {
    display: block;
}

.user-dropdown a {
    display: block;
    padding: 10px 16px;
    color: var(--text-secondary);
    font-size: 14px;
    border-bottom: 1px solid var(--border-light);
}

.user-dropdown a:last-child {
    border-bottom: none;
}

.user-dropdown a:hover {
    background: var(--primary-bg);
    color: var(--primary);
}

/* 按钮 */
.btn {
    display: inline-flex;
    align-items: center;
    justify-content: center;
    padding: 8px 20px;
    border-radius: var(--radius-sm);
    font-size: 14px;
    font-weight: 500;
    cursor: pointer;
    transition: var(--transition);
    border: none;
    outline: none;
    gap: 6px;
}

.btn-primary {
    background: linear-gradient(135deg, var(--primary), var(--secondary));
    color: #fff;
}

.btn-primary:hover {
    opacity: 0.9;
    transform: translateY(-1px);
    box-shadow: var(--shadow-md);
}

.btn-outline {
    background: transparent;
    color: var(--primary);
    border: 1px solid var(--primary);
}

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

.btn-success {
    background: var(--success);
    color: #fff;
}

.btn-danger {
    background: var(--danger);
    color: #fff;
}

.btn-warning {
    background: var(--warning);
    color: #fff;
}

.btn-lg {
    padding: 12px 28px;
    font-size: 16px;
    border-radius: var(--radius-md);
}

.btn-sm {
    padding: 5px 12px;
    font-size: 13px;
}

.btn-block {
    width: 100%;
}

/* 移动端菜单按钮 */
.mobile-menu-btn {
    display: none;
    flex-direction: column;
    gap: 5px;
    background: none;
    border: none;
    cursor: pointer;
    padding: 4px;
}

.mobile-menu-btn span {
    display: block;
    width: 24px;
    height: 2px;
    background: var(--text-primary);
    border-radius: 2px;
    transition: var(--transition);
}

.mobile-menu {
    display: none;
    flex-direction: column;
    background: var(--bg-primary);
    border-top: 1px solid var(--border-color);
    padding: 10px 20px;
}

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

.mobile-nav-link {
    padding: 12px 0;
    color: var(--text-secondary);
    font-size: 15px;
    border-bottom: 1px solid var(--border-light);
}

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

/* ========================================
   Banner / Hero 区域
   ======================================== */
.hero-section {
    background: linear-gradient(135deg, #3b82f6 0%, #8b5cf6 50%, #6366f1 100%);
    color: #fff;
    padding: 80px 0;
    position: relative;
    overflow: hidden;
}

.hero-section::before {
    content: '';
    position: absolute;
    top: -50%;
    right: -20%;
    width: 600px;
    height: 600px;
    background: radial-gradient(circle, rgba(255,255,255,0.1) 0%, transparent 70%);
    border-radius: 50%;
}

.hero-section::after {
    content: '';
    position: absolute;
    bottom: -30%;
    left: -10%;
    width: 400px;
    height: 400px;
    background: radial-gradient(circle, rgba(255,255,255,0.08) 0%, transparent 70%);
    border-radius: 50%;
}

.hero-content {
    position: relative;
    z-index: 1;
    text-align: center;
    max-width: 700px;
    margin: 0 auto;
}

.hero-title {
    font-size: 42px;
    font-weight: 800;
    margin-bottom: 16px;
    line-height: 1.3;
}

.hero-subtitle {
    font-size: 18px;
    opacity: 0.9;
    margin-bottom: 32px;
    line-height: 1.6;
}

.hero-actions {
    display: flex;
    gap: 16px;
    justify-content: center;
    flex-wrap: wrap;
}

.hero-actions .btn {
    padding: 14px 32px;
    font-size: 16px;
    border-radius: var(--radius-md);
}

.hero-actions .btn-white {
    background: #fff;
    color: var(--primary);
}

.hero-actions .btn-ghost {
    background: rgba(255,255,255,0.2);
    color: #fff;
    border: 1px solid rgba(255,255,255,0.4);
}

.hero-actions .btn-ghost:hover {
    background: rgba(255,255,255,0.3);
}

/* ========================================
   通用区块
   ======================================== */
.section {
    padding: 60px 0;
}

.section-header {
    text-align: center;
    margin-bottom: 40px;
}

.section-title {
    font-size: 28px;
    font-weight: 700;
    color: var(--text-primary);
    margin-bottom: 10px;
}

.section-desc {
    font-size: 16px;
    color: var(--text-secondary);
}

/* ========================================
   课程卡片
   ======================================== */
.course-grid {
    display: grid;
    grid-template-columns: repeat(auto-fill, minmax(280px, 1fr));
    gap: 24px;
}

.course-card {
    background: var(--bg-primary);
    border-radius: var(--radius-lg);
    overflow: hidden;
    box-shadow: var(--shadow-sm);
    transition: var(--transition);
    cursor: pointer;
    border: 1px solid var(--border-light);
}

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

.course-card-cover {
    height: 180px;
    background: linear-gradient(135deg, var(--primary-bg), var(--primary-light));
    display: flex;
    align-items: center;
    justify-content: center;
    position: relative;
    overflow: hidden;
}

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

.course-card-cover .placeholder-icon {
    font-size: 48px;
    opacity: 0.5;
}

.course-card-body {
    padding: 16px;
}

.course-card-title {
    font-size: 16px;
    font-weight: 600;
    color: var(--text-primary);
    margin-bottom: 8px;
    display: -webkit-box;
    -webkit-line-clamp: 2;
    -webkit-box-orient: vertical;
    overflow: hidden;
}

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

.course-card-tag {
    display: inline-block;
    padding: 2px 8px;
    background: var(--primary-bg);
    color: var(--primary);
    border-radius: 4px;
    font-size: 12px;
    font-weight: 500;
}

/* ========================================
   新闻卡片
   ======================================== */
.news-grid {
    display: grid;
    grid-template-columns: repeat(auto-fill, minmax(350px, 1fr));
    gap: 24px;
}

.news-card {
    background: var(--bg-primary);
    border-radius: var(--radius-lg);
    overflow: hidden;
    box-shadow: var(--shadow-sm);
    transition: var(--transition);
    border: 1px solid var(--border-light);
}

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

.news-card-cover {
    height: 200px;
    background: linear-gradient(135deg, #e0e7ff, #c7d2fe);
    display: flex;
    align-items: center;
    justify-content: center;
    overflow: hidden;
}

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

.news-card-cover .placeholder-icon {
    font-size: 48px;
    opacity: 0.3;
}

.news-card-body {
    padding: 20px;
}

.news-card-title {
    font-size: 17px;
    font-weight: 600;
    color: var(--text-primary);
    margin-bottom: 8px;
    display: -webkit-box;
    -webkit-line-clamp: 2;
    -webkit-box-orient: vertical;
    overflow: hidden;
}

.news-card-summary {
    font-size: 14px;
    color: var(--text-secondary);
    margin-bottom: 12px;
    display: -webkit-box;
    -webkit-line-clamp: 3;
    -webkit-box-orient: vertical;
    overflow: hidden;
}

.news-card-footer {
    display: flex;
    align-items: center;
    justify-content: space-between;
}

.news-card-date {
    font-size: 13px;
    color: var(--text-light);
}

.news-card-link {
    font-size: 14px;
    color: var(--primary);
    font-weight: 500;
}

.news-card-link:hover {
    color: var(--primary-dark);
}

/* ========================================
   考试卡片
   ======================================== */
.exam-grid {
    display: grid;
    grid-template-columns: repeat(auto-fill, minmax(280px, 1fr));
    gap: 24px;
}

.exam-card {
    background: var(--bg-primary);
    border-radius: var(--radius-lg);
    overflow: hidden;
    box-shadow: var(--shadow-sm);
    transition: var(--transition);
    border: 1px solid var(--border-light);
    position: relative;
}

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

.exam-card-cover {
    height: 180px;
    background: linear-gradient(135deg, #ddd6fe, #c4b5fd);
    display: flex;
    align-items: center;
    justify-content: center;
    overflow: hidden;
}

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

.exam-card-cover .exam-title-placeholder {
    font-size: 20px;
    font-weight: 700;
    color: var(--secondary);
    text-align: center;
    padding: 20px;
}

.exam-card-body {
    padding: 16px;
}

.exam-card-title {
    font-size: 16px;
    font-weight: 600;
    color: var(--text-primary);
    margin-bottom: 8px;
}

.exam-card-meta {
    display: flex;
    align-items: center;
    gap: 12px;
    font-size: 13px;
    color: var(--text-light);
    margin-bottom: 12px;
}

.exam-card-price {
    display: inline-flex;
    align-items: center;
    gap: 4px;
}

.exam-card-price.free {
    color: var(--success);
    font-weight: 600;
}

.exam-card-price.paid {
    color: var(--warning);
    font-weight: 600;
}

.exam-card-top {
    position: absolute;
    top: 12px;
    right: 12px;
    background: var(--danger);
    color: #fff;
    font-size: 12px;
    padding: 2px 8px;
    border-radius: 4px;
    font-weight: 600;
}

/* ========================================
   筛选栏
   ======================================== */
.filter-bar {
    background: var(--bg-primary);
    border-radius: var(--radius-lg);
    padding: 20px 24px;
    margin-bottom: 30px;
    box-shadow: var(--shadow-sm);
    border: 1px solid var(--border-light);
}

.filter-bar-title {
    font-size: 15px;
    font-weight: 600;
    color: var(--text-primary);
    margin-bottom: 12px;
}

.filter-tags {
    display: flex;
    flex-wrap: wrap;
    gap: 8px;
}

.filter-tag {
    padding: 6px 16px;
    border-radius: 20px;
    font-size: 14px;
    color: var(--text-secondary);
    background: var(--bg-tertiary);
    cursor: pointer;
    transition: var(--transition);
    border: 1px solid transparent;
}

.filter-tag:hover,
.filter-tag.active {
    background: var(--primary-bg);
    color: var(--primary);
    border-color: var(--primary);
}

/* ========================================
   页面Banner
   ======================================== */
.page-banner {
    background: linear-gradient(135deg, #3b82f6 0%, #8b5cf6 100%);
    color: #fff;
    padding: 50px 0;
    position: relative;
    overflow: hidden;
}

.page-banner::before {
    content: '';
    position: absolute;
    top: -50%;
    right: -10%;
    width: 400px;
    height: 400px;
    background: radial-gradient(circle, rgba(255,255,255,0.1) 0%, transparent 70%);
    border-radius: 50%;
}

.page-banner-content {
    position: relative;
    z-index: 1;
}

.page-banner-title {
    font-size: 32px;
    font-weight: 700;
    margin-bottom: 8px;
}

.page-banner-desc {
    font-size: 16px;
    opacity: 0.85;
}

/* ========================================
   底部
   ======================================== */
.site-footer {
    background: #1e293b;
    color: #94a3b8;
    padding: 50px 0 20px;
    margin-top: 60px;
}

.footer-inner {
    display: flex;
    justify-content: space-between;
    gap: 40px;
    padding-bottom: 30px;
    border-bottom: 1px solid #334155;
}

.footer-brand {
    max-width: 350px;
}

.footer-logo {
    display: flex;
    align-items: center;
    gap: 8px;
    margin-bottom: 12px;
}

.footer-logo .logo-icon {
    font-size: 24px;
}

.footer-logo-img {
    height: 32px;
    width: auto;
    border-radius: 4px;
    object-fit: contain;
}

.footer-logo .logo-text {
    font-size: 18px;
    font-weight: 700;
    color: #fff;
}

.footer-desc {
    font-size: 14px;
    line-height: 1.6;
}

.footer-links {
    display: flex;
    gap: 60px;
}

.footer-col h4 {
    color: #fff;
    font-size: 15px;
    margin-bottom: 12px;
}

.footer-col a {
    display: block;
    color: #94a3b8;
    font-size: 14px;
    padding: 4px 0;
    transition: var(--transition);
}

.footer-col a:hover {
    color: #fff;
}

.footer-bottom {
    padding-top: 20px;
    text-align: center;
    font-size: 13px;
}

.footer-icp {
    margin-top: 6px;
    font-size: 12px;
    opacity: 0.8;
}

/* ========================================
   表单
   ======================================== */
.form-group {
    margin-bottom: 20px;
}

.form-label {
    display: block;
    margin-bottom: 6px;
    font-size: 14px;
    font-weight: 500;
    color: var(--text-primary);
}

.form-input {
    width: 100%;
    padding: 10px 14px;
    border: 1px solid var(--border-color);
    border-radius: var(--radius-sm);
    font-size: 14px;
    color: var(--text-primary);
    transition: var(--transition);
    background: var(--bg-primary);
}

.form-input:focus {
    outline: none;
    border-color: var(--primary);
    box-shadow: 0 0 0 3px rgba(59, 130, 246, 0.1);
}

.form-hint {
    font-size: 12px;
    color: var(--text-light);
    margin-top: 4px;
}

/* ========================================
   分页
   ======================================== */
.pagination {
    display: flex;
    justify-content: center;
    gap: 8px;
    margin-top: 40px;
}

.pagination a,
.pagination span {
    display: inline-flex;
    align-items: center;
    justify-content: center;
    min-width: 36px;
    height: 36px;
    padding: 0 12px;
    border-radius: var(--radius-sm);
    font-size: 14px;
    border: 1px solid var(--border-color);
    color: var(--text-secondary);
    background: var(--bg-primary);
    transition: var(--transition);
}

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

.pagination .active {
    background: var(--primary);
    color: #fff;
    border-color: var(--primary);
}

/* ========================================
   消息提示
   ======================================== */
.alert {
    padding: 14px 18px;
    border-radius: var(--radius-md);
    margin-bottom: 20px;
    font-size: 14px;
}

.alert-success {
    background: #dcfce7;
    color: #166534;
    border: 1px solid #bbf7d0;
}

.alert-danger {
    background: #fef2f2;
    color: #991b1b;
    border: 1px solid #fecaca;
}

.alert-warning {
    background: #fef9c3;
    color: #854d0e;
    border: 1px solid #fde68a;
}

.alert-info {
    background: #dbeafe;
    color: #1e40af;
    border: 1px solid #bfdbfe;
}

/* ========================================
   空状态
   ======================================== */
.empty-state {
    text-align: center;
    padding: 60px 20px;
    color: var(--text-light);
}

.empty-state-icon {
    font-size: 64px;
    margin-bottom: 16px;
}

.empty-state-text {
    font-size: 16px;
}

/* ========================================
   过渡页面（考试加载）
   ======================================== */
.transition-page {
    min-height: 100vh;
    display: flex;
    align-items: center;
    justify-content: center;
    background: linear-gradient(135deg, #0f172a 0%, #1e1b4b 50%, #312e81 100%);
    position: relative;
    overflow: hidden;
}

.transition-page::before {
    content: '';
    position: absolute;
    width: 200%;
    height: 200%;
    top: -50%;
    left: -50%;
    background: radial-gradient(ellipse at center, rgba(99,102,241,0.3) 0%, transparent 50%),
                radial-gradient(ellipse at 80% 20%, rgba(139,92,246,0.2) 0%, transparent 40%),
                radial-gradient(ellipse at 20% 80%, rgba(59,130,246,0.2) 0%, transparent 40%);
    animation: pulse-bg 4s ease-in-out infinite;
}

@keyframes pulse-bg {
    0%, 100% { transform: scale(1); opacity: 0.8; }
    50% { transform: scale(1.1); opacity: 1; }
}

.transition-content {
    position: relative;
    z-index: 1;
    text-align: center;
    color: #fff;
}

.transition-icon {
    font-size: 80px;
    margin-bottom: 24px;
    animation: float 2s ease-in-out infinite;
}

@keyframes float {
    0%, 100% { transform: translateY(0); }
    50% { transform: translateY(-10px); }
}

.transition-text {
    font-size: 22px;
    font-weight: 600;
    margin-bottom: 12px;
}

.transition-subtext {
    font-size: 16px;
    opacity: 0.7;
}

.loading-dots::after {
    content: '';
    animation: dots 1.5s steps(4, end) infinite;
}

@keyframes dots {
    0% { content: ''; }
    25% { content: '.'; }
    50% { content: '..'; }
    75% { content: '...'; }
}

/* 粒子效果 */
.particles {
    position: absolute;
    width: 100%;
    height: 100%;
    top: 0;
    left: 0;
    overflow: hidden;
}

.particle {
    position: absolute;
    width: 4px;
    height: 4px;
    background: rgba(255,255,255,0.3);
    border-radius: 50%;
    animation: particle-float linear infinite;
}

@keyframes particle-float {
    0% { transform: translateY(100vh) rotate(0deg); opacity: 0; }
    10% { opacity: 1; }
    90% { opacity: 1; }
    100% { transform: translateY(-100vh) rotate(720deg); opacity: 0; }
}

/* ========================================
   考试页面
   ======================================== */
.exam-paper {
    max-width: 900px;
    margin: 30px auto;
    background: var(--bg-primary);
    border-radius: var(--radius-lg);
    box-shadow: var(--shadow-md);
    overflow: hidden;
}

.exam-paper-header {
    background: linear-gradient(135deg, var(--primary), var(--secondary));
    color: #fff;
    padding: 24px 30px;
    display: flex;
    justify-content: space-between;
    align-items: center;
}

.exam-paper-title {
    font-size: 22px;
    font-weight: 700;
}

.exam-timer {
    font-size: 20px;
    font-weight: 700;
    background: rgba(255,255,255,0.2);
    padding: 8px 16px;
    border-radius: var(--radius-sm);
}

.exam-paper-body {
    padding: 30px;
}

.question-section {
    margin-bottom: 30px;
}

.question-section-title {
    font-size: 18px;
    font-weight: 700;
    color: var(--primary);
    margin-bottom: 16px;
    padding-bottom: 8px;
    border-bottom: 2px solid var(--primary-bg);
}

.question-item {
    margin-bottom: 24px;
    padding: 20px;
    background: var(--bg-secondary);
    border-radius: var(--radius-md);
    border: 1px solid var(--border-light);
}

.question-number {
    font-size: 14px;
    font-weight: 600;
    color: var(--primary);
    margin-bottom: 8px;
}

.question-content {
    font-size: 15px;
    color: var(--text-primary);
    margin-bottom: 12px;
    line-height: 1.7;
}

.question-options {
    display: flex;
    flex-direction: column;
    gap: 8px;
}

.question-option {
    display: flex;
    align-items: center;
    gap: 10px;
    padding: 10px 14px;
    background: var(--bg-primary);
    border-radius: var(--radius-sm);
    cursor: pointer;
    transition: var(--transition);
    border: 1px solid var(--border-light);
}

.question-option:hover {
    border-color: var(--primary);
    background: var(--primary-bg);
}

.question-option input[type="radio"],
.question-option input[type="checkbox"] {
    accent-color: var(--primary);
}

.question-option.selected {
    border-color: var(--primary);
    background: var(--primary-bg);
}

.question-answer-input {
    width: 100%;
    padding: 10px 14px;
    border: 1px solid var(--border-color);
    border-radius: var(--radius-sm);
    font-size: 14px;
}

.question-analysis {
    margin-top: 12px;
    padding: 12px 16px;
    background: #f0fdf4;
    border-radius: var(--radius-sm);
    border-left: 3px solid var(--success);
    font-size: 14px;
    color: #166534;
    display: none;
}

.question-result {
    display: flex;
    align-items: center;
    gap: 8px;
    margin-top: 8px;
    font-size: 16px;
    font-weight: 700;
    display: none;
}

.question-result.correct {
    color: var(--success);
}

.question-result.wrong {
    color: var(--danger);
}

.exam-paper-footer {
    padding: 20px 30px;
    text-align: center;
    border-top: 1px solid var(--border-light);
}

/* ========================================
   个人中心
   ======================================== */
.profile-card {
    background: var(--bg-primary);
    border-radius: var(--radius-lg);
    padding: 30px;
    box-shadow: var(--shadow-sm);
    border: 1px solid var(--border-light);
}

.profile-header {
    display: flex;
    align-items: center;
    gap: 20px;
    margin-bottom: 24px;
    padding-bottom: 24px;
    border-bottom: 1px solid var(--border-light);
}

.profile-avatar {
    width: 80px;
    height: 80px;
    border-radius: 50%;
    background: linear-gradient(135deg, var(--primary), var(--secondary));
    display: flex;
    align-items: center;
    justify-content: center;
    font-size: 32px;
    color: #fff;
}

.profile-info h3 {
    font-size: 20px;
    margin-bottom: 4px;
}

.profile-info p {
    font-size: 14px;
    color: var(--text-secondary);
}

/* ========================================
   充值页面
   ======================================== */
.recharge-options {
    display: grid;
    grid-template-columns: repeat(auto-fill, minmax(200px, 1fr));
    gap: 16px;
    margin-bottom: 24px;
}

.recharge-option {
    background: var(--bg-primary);
    border: 2px solid var(--border-color);
    border-radius: var(--radius-md);
    padding: 24px;
    text-align: center;
    cursor: pointer;
    transition: var(--transition);
}

.recharge-option:hover,
.recharge-option.selected {
    border-color: var(--primary);
    background: var(--primary-bg);
}

.recharge-option .amount {
    font-size: 28px;
    font-weight: 700;
    color: var(--primary);
}

.recharge-option .unit {
    font-size: 14px;
    color: var(--text-secondary);
}

.recharge-option .power {
    font-size: 14px;
    color: var(--warning);
    margin-top: 4px;
}

/* VIP卡片 */
.vip-card {
    background: linear-gradient(135deg, #fbbf24, #f59e0b, #d97706);
    border-radius: var(--radius-lg);
    padding: 30px;
    color: #fff;
    margin-bottom: 24px;
    position: relative;
    overflow: hidden;
}

.vip-card::before {
    content: '';
    position: absolute;
    top: -50%;
    right: -20%;
    width: 200px;
    height: 200px;
    background: radial-gradient(circle, rgba(255,255,255,0.2) 0%, transparent 70%);
    border-radius: 50%;
}

.vip-card h3 {
    font-size: 24px;
    margin-bottom: 8px;
}

.vip-card p {
    font-size: 14px;
    opacity: 0.9;
    margin-bottom: 16px;
}

.vip-card .vip-price {
    font-size: 36px;
    font-weight: 800;
}

.vip-card .vip-price small {
    font-size: 16px;
    font-weight: 400;
}

/* ========================================
   响应式
   ======================================== */
@media (max-width: 768px) {
    .main-nav {
        display: none;
    }
    
    .header-right .btn {
        display: none;
    }
    
    .mobile-menu-btn {
        display: flex;
    }
    
    .logo-img {
        height: 40px;
        max-height: 40px;
        width: auto;
        max-width: 120px;
        object-fit: contain;
    }
    
    .logo .logo-text {
        display: none;
    }
    
    .logo .logo-text-short {
        display: inline;
    }
    
    .footer-logo-img {
        height: 40px;
        max-height: 40px;
        width: auto;
        max-width: 120px;
        object-fit: contain;
    }
    
    .hero-title {
        font-size: 28px;
    }
    
    .hero-subtitle {
        font-size: 15px;
    }
    
    .section-title {
        font-size: 22px;
    }
    
    .course-grid,
    .news-grid,
    .exam-grid {
        grid-template-columns: 1fr;
    }
    
    .footer-inner {
        flex-direction: column;
        gap: 30px;
    }
    
    .footer-links {
        gap: 30px;
    }
    
    .page-banner-title {
        font-size: 24px;
    }
    
    .exam-paper-header {
        flex-direction: column;
        gap: 12px;
        text-align: center;
    }
    
    .recharge-options {
        grid-template-columns: repeat(2, 1fr);
    }
}

@media (max-width: 480px) {
    .container {
        padding: 0 12px;
    }
    
    .hero-section {
        padding: 50px 0;
    }
    
    .hero-title {
        font-size: 24px;
    }
    
    .recharge-options {
        grid-template-columns: 1fr;
    }
}