/* 基础样式重置 */
* {
    margin: 0;
    padding: 0;
    box-sizing: border-box;
}

body {
    font-family: 'Microsoft YaHei', 'SimHei', Arial, sans-serif;
    background: linear-gradient(135deg, #f5f7fa 0%, #c3cfe2 100%);
    min-height: 100vh;
    color: #333;
}

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

/* 导航栏样式 */
.main-nav {
    background: white;
    border-radius: 15px;
    box-shadow: 0 5px 20px rgba(0,0,0,0.1);
    padding: 15px 25px;
    margin-bottom: 30px;
    display: flex;
    justify-content: space-between;
    align-items: center;
    flex-wrap: wrap;
    gap: 15px;
}

.nav-brand {
    display: flex;
    align-items: center;
    gap: 10px;
    font-size: 1.3em;
    font-weight: bold;
    color: #2c3e50;
}

.brand-icon {
    font-size: 1.5em;
}

.nav-links {
    display: flex;
    gap: 15px;
    flex-wrap: wrap;
}

.nav-link {
    text-decoration: none;
    color: #666;
    padding: 8px 16px;
    border-radius: 20px;
    transition: all 0.3s ease;
    font-size: 0.9em;
}

.nav-link:hover {
    background: #f0f2f5;
    color: #2c3e50;
    transform: translateY(-2px);
}

.nav-link.active {
    background: linear-gradient(135deg, #667eea, #764ba2);
    color: white;
}

/* 欢迎动画区域 */
.welcome-section {
    background: linear-gradient(135deg, #667eea 0%, #764ba2 100%);
    border-radius: 20px;
    padding: 40px;
    margin-bottom: 40px;
    text-align: center;
    color: white;
    box-shadow: 0 10px 30px rgba(0,0,0,0.2);
    position: relative;
    overflow: hidden;
}

.welcome-section::before {
    content: '';
    position: absolute;
    top: -50%;
    left: -50%;
    width: 200%;
    height: 200%;
    background: radial-gradient(circle, rgba(255,255,255,0.1) 0%, transparent 70%);
    animation: rotate 20s linear infinite;
}

@keyframes rotate {
    from { transform: rotate(0deg); }
    to { transform: rotate(360deg); }
}

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

.welcome-title {
    font-size: 3em;
    margin-bottom: 15px;
    text-shadow: 2px 2px 4px rgba(0,0,0,0.3);
    animation: fadeInDown 1s ease-out;
}

.welcome-subtitle {
    font-size: 1.4em;
    margin-bottom: 30px;
    opacity: 0.9;
    animation: fadeInUp 1s ease-out 0.3s both;
}

.welcome-animation {
    display: flex;
    justify-content: center;
    gap: 20px;
    margin-bottom: 30px;
    animation: fadeInUp 1s ease-out 0.6s both;
}

.fraction-animation {
    display: flex;
    flex-direction: column;
    align-items: center;
    gap: 5px;
    animation: bounce 2s ease-in-out infinite;
}

.fraction-animation:nth-child(2) { animation-delay: 0.5s; }
.fraction-animation:nth-child(3) { animation-delay: 1s; }

.fraction-num, .fraction-den {
    font-size: 1.5em;
    font-weight: bold;
    color: #ffd700;
    text-shadow: 1px 1px 2px rgba(0,0,0,0.5);
}

.fraction-line {
    width: 30px;
    height: 3px;
    background: #ffd700;
    border-radius: 2px;
    box-shadow: 1px 1px 2px rgba(0,0,0,0.3);
}

.welcome-buttons {
    display: flex;
    gap: 20px;
    justify-content: center;
    flex-wrap: wrap;
    animation: fadeInUp 1s ease-out 0.9s both;
}

.welcome-btn {
    padding: 12px 30px;
    border: none;
    border-radius: 25px;
    font-size: 1.1em;
    font-weight: bold;
    cursor: pointer;
    transition: all 0.3s ease;
    text-decoration: none;
    display: inline-block;
}

.welcome-btn.primary {
    background: linear-gradient(135deg, #ffd700, #ffed4e);
    color: #333;
    box-shadow: 0 5px 15px rgba(255, 215, 0, 0.4);
}

.welcome-btn.primary:hover {
    transform: translateY(-3px);
    box-shadow: 0 8px 25px rgba(255, 215, 0, 0.6);
}

.welcome-btn.secondary {
    background: rgba(255,255,255,0.2);
    color: white;
    border: 2px solid rgba(255,255,255,0.3);
}

.welcome-btn.secondary:hover {
    background: rgba(255,255,255,0.3);
    transform: translateY(-3px);
}

/* 通用标题样式 */
.section-title {
    font-size: 1.8em;
    color: #2c3e50;
    margin-bottom: 25px;
    text-align: center;
    position: relative;
}

.section-title::after {
    content: '';
    position: absolute;
    bottom: -8px;
    left: 50%;
    transform: translateX(-50%);
    width: 60px;
    height: 3px;
    background: linear-gradient(135deg, #667eea, #764ba2);
    border-radius: 2px;
}

/* 主要内容区域 */
.main-section {
    margin-bottom: 40px;
}

.card-row {
    display: grid;
    grid-template-columns: repeat(auto-fit, minmax(280px, 1fr));
    gap: 25px;
}

.learning-card {
    background: white;
    border-radius: 15px;
    padding: 25px;
    box-shadow: 0 5px 20px rgba(0,0,0,0.1);
    transition: all 0.3s ease;
    cursor: pointer;
    position: relative;
    overflow: hidden;
    animation: fadeInUp 0.6s ease-out;
}

.learning-card::before {
    content: '';
    position: absolute;
    top: 0;
    left: -100%;
    width: 100%;
    height: 100%;
    background: linear-gradient(90deg, transparent, rgba(255,255,255,0.4), transparent);
    transition: left 0.5s ease;
}

.learning-card:hover::before {
    left: 100%;
}

.learning-card:hover {
    transform: translateY(-10px);
    box-shadow: 0 15px 40px rgba(0,0,0,0.15);
}

.learning-card.secondary {
    background: linear-gradient(135deg, #f8f9fa, #e9ecef);
}

.learning-card.secondary:hover {
    background: linear-gradient(135deg, #e9ecef, #dee2e6);
}

.card-icon {
    font-size: 2.5em;
    margin-bottom: 15px;
    display: block;
}

.learning-card h3 {
    font-size: 1.3em;
    margin-bottom: 10px;
    color: #2c3e50;
}

.learning-card p {
    color: #666;
    line-height: 1.5;
    margin-bottom: 15px;
}

/* 卡片进度条 */
.card-progress {
    margin-top: 15px;
}

.progress-bar {
    width: 100%;
    height: 6px;
    background: #e9ecef;
    border-radius: 3px;
    overflow: hidden;
    margin-bottom: 8px;
}

.progress-fill {
    height: 100%;
    background: linear-gradient(135deg, #28a745, #20c997);
    border-radius: 3px;
    transition: width 0.8s ease;
}

.progress-text {
    font-size: 0.85em;
    color: #666;
    font-weight: 500;
}

/* 卡片徽章 */
.card-badge {
    position: absolute;
    top: 15px;
    right: 15px;
    background: linear-gradient(135deg, #ff6b6b, #ee5a24);
    color: white;
    padding: 4px 12px;
    border-radius: 12px;
    font-size: 0.75em;
    font-weight: bold;
    box-shadow: 0 2px 8px rgba(255, 107, 107, 0.3);
}

.additional-section {
    margin-bottom: 40px;
}

.additional-section h3 {
    margin-bottom: 25px;
}

/* 学习进度展示 */
.progress-section {
    margin-bottom: 40px;
}

.progress-section h3 {
    margin-bottom: 25px;
}

.progress-cards {
    display: grid;
    grid-template-columns: repeat(auto-fit, minmax(300px, 1fr));
    gap: 25px;
}

.progress-card {
    background: white;
    border-radius: 15px;
    padding: 25px;
    box-shadow: 0 5px 20px rgba(0,0,0,0.1);
    display: flex;
    align-items: center;
    gap: 20px;
    transition: all 0.3s ease;
}

.progress-card:hover {
    transform: translateY(-5px);
    box-shadow: 0 10px 30px rgba(0,0,0,0.15);
}

.progress-icon {
    font-size: 2.5em;
    width: 60px;
    height: 60px;
    display: flex;
    align-items: center;
    justify-content: center;
    background: linear-gradient(135deg, #667eea, #764ba2);
    color: white;
    border-radius: 50%;
    flex-shrink: 0;
}

.progress-info h4 {
    font-size: 1.2em;
    margin-bottom: 8px;
    color: #2c3e50;
}

.progress-info p {
    color: #666;
    margin-bottom: 10px;
}

.progress-info span {
    color: #667eea;
    font-weight: bold;
    font-size: 1.1em;
}

/* 迷你进度条 */
.mini-progress {
    width: 100%;
    height: 4px;
    background: #e9ecef;
    border-radius: 2px;
    overflow: hidden;
}

.mini-progress-fill {
    height: 100%;
    background: linear-gradient(135deg, #28a745, #20c997);
    border-radius: 2px;
    width: 0%;
    transition: width 0.8s ease;
}

/* 连续学习指示器 */
.streak-indicator {
    background: linear-gradient(135deg, #ff6b6b, #ee5a24);
    color: white;
    padding: 4px 12px;
    border-radius: 12px;
    font-size: 0.8em;
    font-weight: bold;
    display: inline-block;
}

/* 星星显示 */
.stars-display {
    display: flex;
    gap: 2px;
}

.stars-display::before {
    content: '⭐'.repeat(5);
    font-size: 0.9em;
}

/* 学习统计图表 */
.stats-section {
    margin-bottom: 40px;
}

.stats-container {
    display: grid;
    grid-template-columns: 1fr auto;
    gap: 30px;
    align-items: start;
}

.stats-chart {
    background: white;
    border-radius: 15px;
    padding: 25px;
    box-shadow: 0 5px 20px rgba(0,0,0,0.1);
    text-align: center;
}

.stats-chart h4 {
    margin-top: 15px;
    color: #2c3e50;
}

.stats-summary {
    display: flex;
    flex-direction: column;
    gap: 20px;
}

.stat-item {
    background: white;
    border-radius: 15px;
    padding: 20px;
    box-shadow: 0 5px 20px rgba(0,0,0,0.1);
    text-align: center;
    transition: all 0.3s ease;
}

.stat-item:hover {
    transform: translateY(-3px);
    box-shadow: 0 10px 30px rgba(0,0,0,0.15);
}

.stat-number {
    font-size: 2em;
    font-weight: bold;
    color: #667eea;
    margin-bottom: 8px;
}

.stat-label {
    color: #666;
    font-size: 0.9em;
}

/* 快速开始区域 */
.quick-start-section {
    margin-bottom: 40px;
}

.quick-start-grid {
    display: grid;
    grid-template-columns: repeat(auto-fit, minmax(200px, 1fr));
    gap: 20px;
}

.quick-start-item {
    background: white;
    border-radius: 15px;
    padding: 25px;
    box-shadow: 0 5px 20px rgba(0,0,0,0.1);
    text-align: center;
    cursor: pointer;
    transition: all 0.3s ease;
    display: flex;
    flex-direction: column;
    align-items: center;
    gap: 15px;
}

.quick-start-item:hover {
    transform: translateY(-5px);
    box-shadow: 0 10px 30px rgba(0,0,0,0.15);
    background: linear-gradient(135deg, #f8f9fa, #e9ecef);
}

.quick-icon {
    font-size: 2.5em;
    width: 60px;
    height: 60px;
    display: flex;
    align-items: center;
    justify-content: center;
    background: linear-gradient(135deg, #667eea, #764ba2);
    color: white;
    border-radius: 50%;
}

.quick-start-item span {
    font-weight: bold;
    color: #2c3e50;
    font-size: 1.1em;
}

/* 响应式设计 */
@media (max-width: 768px) {
    .container {
        padding: 15px;
    }
    
    .main-nav {
        flex-direction: column;
        text-align: center;
    }
    
    .nav-links {
        justify-content: center;
    }
    
    .welcome-title {
        font-size: 2.2em;
    }
    
    .welcome-animation {
        flex-direction: column;
        gap: 15px;
    }
    
    .welcome-buttons {
        flex-direction: column;
        align-items: center;
    }
    
    .card-row {
        grid-template-columns: 1fr;
    }
    
    .learning-card {
        padding: 20px;
    }
    
    .card-icon {
        font-size: 2em;
    }
    
    .learning-card h3 {
        font-size: 1.2em;
    }
    
    .learning-card p {
        font-size: 0.9em;
    }
    
    .progress-cards {
        grid-template-columns: 1fr;
    }
    
    .stats-container {
        grid-template-columns: 1fr;
    }
    
    .quick-start-grid {
        grid-template-columns: repeat(2, 1fr);
    }
}

@media (max-width: 480px) {
    .learning-card {
        padding: 15px;
    }
    
    .card-icon {
        font-size: 1.8em;
    }
    
    .learning-card h3 {
        font-size: 1.1em;
    }
    
    .learning-card p {
        font-size: 0.85em;
    }
    
    .nav-link {
        padding: 6px 12px;
        font-size: 0.8em;
    }
    
    .quick-start-grid {
        grid-template-columns: 1fr;
    }
}

/* 动画效果 */
@keyframes fadeInUp {
    from {
        opacity: 0;
        transform: translateY(30px);
    }
    to {
        opacity: 1;
        transform: translateY(0);
    }
}

.learning-card {
    animation: fadeInUp 0.6s ease-out;
}

.learning-card:nth-child(1) { animation-delay: 0.1s; }
.learning-card:nth-child(2) { animation-delay: 0.2s; }
.learning-card:nth-child(3) { animation-delay: 0.3s; }
.learning-card:nth-child(4) { animation-delay: 0.4s; }

.learning-card:hover .card-icon {
    animation: bounce 0.6s ease-in-out;
}

@keyframes bounce {
    0%, 20%, 50%, 80%, 100% { transform: translateY(0); }
    40% { transform: translateY(-10px); }
    60% { transform: translateY(-5px); }
}

@keyframes fadeInDown {
    from {
        opacity: 0;
        transform: translateY(-30px);
    }
    to {
        opacity: 1;
        transform: translateY(0);
    }
} 

/* 听一听栏目样式 */
.listen-section {
    margin-bottom: 40px;
}

.listen-content {
    display: grid;
    grid-template-columns: 2fr 1fr;
    gap: 30px;
    align-items: start;
}

.listen-card {
    background: white;
    border-radius: 15px;
    padding: 30px;
    box-shadow: 0 5px 20px rgba(0,0,0,0.1);
    cursor: pointer;
    transition: all 0.3s ease;
    position: relative;
    overflow: hidden;
}

.listen-card::before {
    content: '';
    position: absolute;
    top: 0;
    left: -100%;
    width: 100%;
    height: 100%;
    background: linear-gradient(90deg, transparent, rgba(102, 126, 234, 0.1), transparent);
    transition: left 0.5s ease;
}

.listen-card:hover::before {
    left: 100%;
}

.listen-card:hover {
    transform: translateY(-5px);
    box-shadow: 0 15px 40px rgba(0,0,0,0.15);
}

.listen-icon {
    font-size: 3em;
    margin-bottom: 20px;
    display: block;
    text-align: center;
    background: linear-gradient(135deg, #667eea, #764ba2);
    -webkit-background-clip: text;
    -webkit-text-fill-color: transparent;
    background-clip: text;
}

.listen-info h4 {
    font-size: 1.4em;
    color: #2c3e50;
    margin-bottom: 15px;
    text-align: center;
}

.listen-info p {
    color: #666;
    line-height: 1.6;
    margin-bottom: 20px;
    text-align: center;
}

.listen-features {
    display: flex;
    gap: 10px;
    justify-content: center;
    flex-wrap: wrap;
    margin-bottom: 25px;
}

.feature-tag {
    background: linear-gradient(135deg, #f8f9fa, #e9ecef);
    color: #495057;
    padding: 6px 12px;
    border-radius: 15px;
    font-size: 0.85em;
    font-weight: 500;
    border: 1px solid #dee2e6;
    transition: all 0.3s ease;
}

.feature-tag:hover {
    background: linear-gradient(135deg, #667eea, #764ba2);
    color: white;
    transform: translateY(-2px);
}

.listen-action {
    display: flex;
    align-items: center;
    justify-content: center;
    gap: 15px;
}

.listen-btn {
    background: linear-gradient(135deg, #667eea, #764ba2);
    color: white;
    border: none;
    padding: 12px 25px;
    border-radius: 25px;
    font-size: 1.1em;
    font-weight: bold;
    cursor: pointer;
    transition: all 0.3s ease;
    box-shadow: 0 5px 15px rgba(102, 126, 234, 0.3);
}

.listen-btn:hover {
    transform: translateY(-3px);
    box-shadow: 0 8px 25px rgba(102, 126, 234, 0.4);
}

.listen-arrow {
    font-size: 1.5em;
    color: #667eea;
    font-weight: bold;
    transition: transform 0.3s ease;
}

.listen-card:hover .listen-arrow {
    transform: translateX(5px);
}

.listen-preview {
    background: white;
    border-radius: 15px;
    padding: 25px;
    box-shadow: 0 5px 20px rgba(0,0,0,0.1);
}

.listen-preview h4 {
    font-size: 1.2em;
    color: #2c3e50;
    margin-bottom: 20px;
    text-align: center;
}

.topic-list {
    display: flex;
    flex-direction: column;
    gap: 15px;
}

.topic-item {
    display: flex;
    align-items: center;
    gap: 12px;
    padding: 12px 15px;
    background: #f8f9fa;
    border-radius: 10px;
    transition: all 0.3s ease;
    cursor: pointer;
}

.topic-item:hover {
    background: #e9ecef;
    transform: translateX(5px);
}

.topic-icon {
    font-size: 1.3em;
    width: 35px;
    height: 35px;
    display: flex;
    align-items: center;
    justify-content: center;
    background: linear-gradient(135deg, #667eea, #764ba2);
    color: white;
    border-radius: 50%;
    flex-shrink: 0;
}

.topic-text {
    color: #495057;
    font-weight: 500;
    font-size: 0.95em;
}

/* 响应式设计 - 听一听栏目 */
@media (max-width: 768px) {
    .listen-content {
        grid-template-columns: 1fr;
        gap: 20px;
    }
    
    .listen-card {
        padding: 25px;
    }
    
    .listen-features {
        gap: 8px;
    }
    
    .feature-tag {
        padding: 5px 10px;
        font-size: 0.8em;
    }
}

@media (max-width: 480px) {
    .listen-card {
        padding: 20px;
    }
    
    .listen-icon {
        font-size: 2.5em;
    }
    
    .listen-info h4 {
        font-size: 1.2em;
    }
    
    .listen-info p {
        font-size: 0.9em;
    }
    
    .feature-tag {
        padding: 4px 8px;
        font-size: 0.75em;
    }
    
    .topic-item {
        padding: 10px 12px;
    }
    
    .topic-icon {
        width: 30px;
        height: 30px;
        font-size: 1.1em;
    }
}

/* 波纹动画 */
@keyframes ripple {
    to {
        transform: scale(4);
        opacity: 0;
    }
}

/* 话题项目淡入动画 */
.topic-item.fade-in-up {
    animation: fadeInUp 0.6s ease forwards;
    opacity: 0;
    transform: translateY(20px);
}