/* 全局样式 */
* {
    margin: 0;
    padding: 0;
    box-sizing: border-box;
}

:root {
    --primary-color: #3498db;
    --secondary-color: #2ecc71;
    --accent-color: #9b59b6;
    --text-dark: #2c3e50;
    --text-light: #7f8c8d;
    --bg-light: #f8f9fa;
    --bg-white: #ffffff;
    --border-color: #e0e0e0;
    --shadow: 0 2px 10px rgba(0, 0, 0, 0.1);
    --shadow-lg: 0 10px 30px rgba(0, 0, 0, 0.15);
    --transition: all 0.3s ease;
}

body {
    font-family: -apple-system, BlinkMacSystemFont, 'Segoe UI', Roboto, 'Helvetica Neue', Arial, sans-serif;
    line-height: 1.6;
    color: var(--text-dark);
    background-color: var(--bg-white);
}

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

/* 导航栏 */
.navbar {
    background: var(--bg-white);
    box-shadow: var(--shadow);
    position: sticky;
    top: 0;
    z-index: 1000;
    padding: 1rem 0;
}

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

.nav-brand h1 {
    font-size: 1.5rem;
    color: var(--primary-color);
    font-weight: 700;
}

.nav-menu {
    display: flex;
    list-style: none;
    gap: 2rem;
    align-items: center;
}

.nav-menu a {
    text-decoration: none;
    color: var(--text-dark);
    font-weight: 500;
    transition: var(--transition);
    position: relative;
}

.nav-menu a:hover,
.nav-menu a.active {
    color: var(--primary-color);
}

.nav-menu a.active::after {
    content: '';
    position: absolute;
    bottom: -5px;
    left: 0;
    width: 100%;
    height: 2px;
    background: var(--primary-color);
}

.btn-download {
    background: var(--primary-color);
    color: white !important;
    padding: 0.5rem 1.5rem;
    border-radius: 25px;
    transition: var(--transition);
}

.btn-download:hover {
    background: #2980b9;
    transform: translateY(-2px);
}

/* 管理入口链接 */
.admin-links {
    display: flex;
    align-items: center;
    gap: 0.5rem;
    margin-left: 1rem;
    padding-left: 1rem;
    border-left: 1px solid var(--border-color);
}

.admin-link {
    color: var(--text-light) !important;
    font-size: 0.9rem;
    text-decoration: none;
    transition: var(--transition);
    padding: 0.3rem 0.8rem;
    border-radius: 4px;
}

.admin-link:hover {
    color: var(--primary-color) !important;
    background: rgba(52, 152, 219, 0.1);
}

.separator {
    color: var(--text-light);
    font-size: 0.9rem;
}

.nav-toggle {
    display: none;
    flex-direction: column;
    background: none;
    border: none;
    cursor: pointer;
    gap: 4px;
}

.nav-toggle span {
    width: 25px;
    height: 3px;
    background: var(--text-dark);
    transition: var(--transition);
}

/* 英雄区域 */
.hero {
    padding: 4rem 0;
    background: linear-gradient(135deg, #667eea 0%, #764ba2 100%);
    color: white;
    min-height: 80vh;
    display: flex;
    align-items: center;
}

.hero .container {
    display: grid;
    grid-template-columns: 1fr 1fr;
    gap: 4rem;
    align-items: center;
}

.hero-title {
    font-size: 3rem;
    font-weight: 700;
    margin-bottom: 1rem;
    line-height: 1.2;
}

.hero-subtitle {
    font-size: 2.5rem;
    margin-bottom: 2rem;
    opacity: 0.9;
}

.hero-buttons {
    display: flex;
    gap: 1rem;
    margin-bottom: 3rem;
}

.btn {
    padding: 0.75rem 2rem;
    border-radius: 30px;
    text-decoration: none;
    font-weight: 600;
    transition: var(--transition);
    display: inline-block;
    border: 2px solid transparent;
}

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

.btn-primary:hover {
    transform: translateY(-2px);
    box-shadow: var(--shadow-lg);
}

.btn-secondary {
    background: transparent;
    color: white;
    border-color: white;
}

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

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

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

.hero-stats {
    display: flex;
    gap: 3rem;
}

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

.stat-number {
    font-size: 2.5rem;
    font-weight: 700;
    margin-bottom: 0.5rem;
}

.stat-label {
    font-size: 0.9rem;
    opacity: 0.8;
}

/* 手机预览 */
.phone-mockup {
    position: relative;
    max-width: 300px;
    margin: 0 auto;
}

.phone-screen {
    background: #1a1a1a;
    border-radius: 30px;
    padding: 15px;
    box-shadow: var(--shadow-lg);
}

.app-preview {
    background: white;
    border-radius: 20px;
    overflow: hidden;
    min-height: 500px;
}

.preview-header {
    background: var(--primary-color);
    color: white;
    padding: 1rem;
    text-align: center;
    font-weight: 600;
}

.preview-content {
    padding: 1rem;
}

.preview-grid {
    display: grid;
    grid-template-columns: repeat(3, 1fr);
    gap: 1rem;
}

.preview-item {
    aspect-ratio: 1;
    background: linear-gradient(135deg, #667eea 0%, #764ba2 100%);
    border-radius: 10px;
    opacity: 0.7;
}

/* 功能区域 */
.features-section {
    padding: 5rem 0;
    background: var(--bg-light);
}

.section-title {
    text-align: center;
    font-size: 2.5rem;
    font-weight: 700;
    margin-bottom: 3rem;
    color: var(--text-dark);
}

.features-grid {
    display: grid;
    grid-template-columns: repeat(auto-fit, minmax(300px, 1fr));
    gap: 2rem;
}

.feature-card {
    background: white;
    padding: 2rem;
    border-radius: 15px;
    box-shadow: var(--shadow);
    transition: var(--transition);
    text-align: center;
}

.feature-card:hover {
    transform: translateY(-5px);
    box-shadow: var(--shadow-lg);
}

.feature-icon {
    font-size: 3rem;
    margin-bottom: 1rem;
}

.feature-card h3 {
    font-size: 1.5rem;
    margin-bottom: 1rem;
    color: var(--text-dark);
}

.feature-card p {
    color: var(--text-light);
    line-height: 1.6;
}

/* 为什么选择我们 */
.why-section {
    padding: 5rem 0;
}

.why-grid {
    display: grid;
    grid-template-columns: repeat(auto-fit, minmax(250px, 1fr));
    gap: 2rem;
}

.why-item {
    text-align: center;
    padding: 2rem;
}

.why-icon {
    font-size: 3rem;
    margin-bottom: 1rem;
}

.why-item h3 {
    font-size: 1.25rem;
    margin-bottom: 0.5rem;
    color: var(--text-dark);
}

.why-item p {
    color: var(--text-light);
}

/* 下载区域 */
.download-section {
    padding: 5rem 0;
    background: linear-gradient(135deg, #667eea 0%, #764ba2 100%);
    color: white;
    text-align: center;
}

.download-content h2 {
    font-size: 2.5rem;
    margin-bottom: 1rem;
}

.download-content > p {
    font-size: 1.25rem;
    margin-bottom: 2rem;
    opacity: 0.9;
}

.download-buttons {
    display: flex;
    justify-content: center;
    gap: 1rem;
    margin-bottom: 1rem;
}

.btn-app-store {
    display: inline-block;
    transition: var(--transition);
}

.btn-app-store:hover {
    transform: scale(1.05);
}

.download-note {
    font-size: 0.9rem;
    opacity: 0.8;
    font-style: italic;
}

/* 页脚 */
.footer {
    background: var(--text-dark);
    color: white;
    padding: 3rem 0 1rem;
}

.footer-content {
    display: grid;
    grid-template-columns: repeat(auto-fit, minmax(250px, 1fr));
    gap: 2rem;
    margin-bottom: 2rem;
}

.footer-section h3,
.footer-section h4 {
    margin-bottom: 1rem;
}

.footer-section ul {
    list-style: none;
}

.footer-section ul li {
    margin-bottom: 0.5rem;
}

.footer-section a {
    color: rgba(255, 255, 255, 0.7);
    text-decoration: none;
    transition: var(--transition);
}

.footer-section a:hover {
    color: white;
}

.footer-bottom {
    text-align: center;
    padding-top: 2rem;
    border-top: 1px solid rgba(255, 255, 255, 0.1);
    color: rgba(255, 255, 255, 0.7);
}

.footer-bottom p {
    margin-bottom: 0.5rem;
}

.icp-info {
    margin-top: 1rem;
    font-size: 0.85rem;
    line-height: 1.8;
}

.icp-info p {
    margin: 0.3rem 0;
}

.icp-info a {
    color: rgba(255, 255, 255, 0.7);
    text-decoration: none;
    transition: var(--transition);
}

.icp-info a:hover {
    color: rgba(255, 255, 255, 0.9);
    text-decoration: underline;
}

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

/* 页面标题区域 */
.page-header {
    background: linear-gradient(135deg, #667eea 0%, #764ba2 100%);
    color: white;
    padding: 4rem 0;
    text-align: center;
}

.page-header h1 {
    font-size: 3rem;
    font-weight: 700;
    margin-bottom: 1rem;
}

.page-header p {
    font-size: 1.25rem;
    opacity: 0.9;
}

/* 功能详情页面 */
.features-detail {
    padding: 4rem 0;
    background: var(--bg-light);
}

.feature-detail-grid {
    display: grid;
    grid-template-columns: repeat(auto-fit, minmax(300px, 1fr));
    gap: 2rem;
}

.feature-detail-card {
    background: white;
    padding: 2rem;
    border-radius: 15px;
    box-shadow: var(--shadow);
    transition: var(--transition);
}

.feature-detail-card:hover {
    transform: translateY(-5px);
    box-shadow: var(--shadow-lg);
}

.feature-detail-icon {
    font-size: 3rem;
    margin-bottom: 1rem;
}

.feature-detail-card h3 {
    font-size: 1.5rem;
    margin-bottom: 1rem;
    color: var(--text-dark);
}

.feature-detail-card p {
    color: var(--text-light);
    line-height: 1.6;
}

/* 学习系统 */
.learning-system {
    padding: 4rem 0;
    background: white;
}

.system-grid {
    display: grid;
    grid-template-columns: repeat(auto-fit, minmax(200px, 1fr));
    gap: 2rem;
    margin-top: 2rem;
}

.system-item {
    text-align: center;
    padding: 2rem;
}

.system-number {
    width: 60px;
    height: 60px;
    background: var(--primary-color);
    color: white;
    border-radius: 50%;
    display: flex;
    align-items: center;
    justify-content: center;
    font-size: 2rem;
    font-weight: 700;
    margin: 0 auto 1rem;
}

.system-item h3 {
    font-size: 1.25rem;
    margin-bottom: 0.5rem;
    color: var(--text-dark);
}

.system-item p {
    color: var(--text-light);
}

/* 关于页面 */
.about-content {
    padding: 4rem 0;
}

.about-section {
    margin-bottom: 4rem;
}

.about-section h2 {
    font-size: 2rem;
    color: var(--text-dark);
    margin-bottom: 1.5rem;
    border-bottom: 3px solid var(--primary-color);
    padding-bottom: 0.5rem;
}

.about-section p {
    color: var(--text-light);
    line-height: 1.8;
    margin-bottom: 1rem;
}

.about-features {
    display: grid;
    grid-template-columns: repeat(auto-fit, minmax(250px, 1fr));
    gap: 2rem;
    margin-top: 2rem;
}

.about-feature-item {
    background: var(--bg-light);
    padding: 1.5rem;
    border-radius: 10px;
    transition: var(--transition);
}

.about-feature-item:hover {
    transform: translateY(-3px);
    box-shadow: var(--shadow);
}

.about-feature-item h3 {
    font-size: 1.25rem;
    margin-bottom: 0.5rem;
    color: var(--text-dark);
}

.about-feature-item p {
    color: var(--text-light);
    font-size: 0.95rem;
}

.tech-list {
    list-style: none;
    padding-left: 0;
}

.tech-list li {
    padding: 1rem;
    margin-bottom: 0.5rem;
    background: var(--bg-light);
    border-left: 4px solid var(--primary-color);
    border-radius: 5px;
    color: var(--text-light);
}

.tech-list li strong {
    color: var(--text-dark);
}

.contact-info-box {
    background: var(--bg-light);
    padding: 2rem;
    border-radius: 10px;
    margin-top: 1rem;
}

.contact-item {
    margin-bottom: 1rem;
    color: var(--text-light);
}

.contact-item strong {
    color: var(--text-dark);
    margin-right: 0.5rem;
}

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

.contact-item a:hover {
    text-decoration: underline;
}

/* 响应式设计 */
@media (max-width: 768px) {
    .nav-menu {
        position: fixed;
        left: -100%;
        top: 70px;
        flex-direction: column;
        background: white;
        width: 100%;
        text-align: center;
        transition: 0.3s;
        box-shadow: var(--shadow);
        padding: 2rem 0;
    }

    .nav-menu.active {
        left: 0;
    }

    .nav-toggle {
        display: flex;
    }

    .admin-links {
        margin-left: 0;
        padding-left: 0;
        border-left: none;
        border-top: 1px solid var(--border-color);
        padding-top: 1rem;
        margin-top: 1rem;
        justify-content: center;
    }

    .hero .container {
        grid-template-columns: 1fr;
        text-align: center;
    }

    .hero-title {
        font-size: 2rem;
    }

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

    .hero-buttons {
        flex-direction: column;
        align-items: center;
    }

    .features-grid,
    .why-grid {
        grid-template-columns: 1fr;
    }

    .section-title {
        font-size: 2rem;
    }
}

@media (max-width: 480px) {
    .hero-title {
        font-size: 1.75rem;
    }

    .hero-subtitle {
        font-size: 2rem;
    }

    .stat-number {
        font-size: 2rem;
    }
}