/* 基础重置和变量 */
* {
    margin: 0;
    padding: 0;
    box-sizing: border-box;
}

:root {
    --primary-color: #667eea;
    --primary-gradient: linear-gradient(135deg, #667eea 0%, #764ba2 100%);
    --secondary-color: #f093fb;
    --secondary-gradient: linear-gradient(135deg, #f093fb 0%, #f5576c 100%);
    --accent-color: #4facfe;
    --text-dark: #2d3748;
    --text-light: #718096;
    --bg-light: #f7fafc;
    --white: #ffffff;
    --shadow: 0 10px 25px rgba(0, 0, 0, 0.1);
    --shadow-hover: 0 20px 40px rgba(0, 0, 0, 0.15);
    --border-radius: 12px;
    --transition: all 0.3s cubic-bezier(0.4, 0, 0.2, 1);
}

body {
    font-family: 'Inter', sans-serif;
    line-height: 1.6;
    color: var(--text-dark);
    overflow-x: hidden;
}

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

/* 导航栏 */
.navbar {
    position: fixed;
    top: 0;
    width: 100%;
    background: rgba(255, 255, 255, 0.95);
    backdrop-filter: blur(10px);
    z-index: 1000;
    transition: var(--transition);
}

.nav-container {
    max-width: 1200px;
    margin: 0 auto;
    padding: 0 20px;
    display: flex;
    justify-content: space-between;
    align-items: center;
    height: 70px;
}

.nav-logo {
    display: flex;
    align-items: center;
    font-size: 1.5rem;
    font-weight: 700;
    color: var(--primary-color);
}

.nav-logo i {
    margin-right: 8px;
    font-size: 1.8rem;
}

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

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

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

.nav-link::after {
    content: '';
    position: absolute;
    bottom: -5px;
    left: 0;
    width: 0;
    height: 2px;
    background: var(--primary-gradient);
    transition: var(--transition);
}

.nav-link:hover::after {
    width: 100%;
}

.hamburger {
    display: none;
    flex-direction: column;
    cursor: pointer;
}

.hamburger span {
    width: 25px;
    height: 3px;
    background: var(--text-dark);
    margin: 3px 0;
    transition: var(--transition);
}

/* 英雄区域 */
.hero {
    min-height: 100vh;
    background: linear-gradient(135deg, #667eea 0%, #764ba2 50%, #f093fb 100%);
    display: flex;
    align-items: center;
    position: relative;
    overflow: hidden;
}

.hero-container {
    display: grid;
    grid-template-columns: 1fr 1fr;
    gap: 4rem;
    align-items: center;
    max-width: 1200px;
    margin: 0 auto;
    padding: 0 20px;
    z-index: 2;
}

.hero-content {
    color: white;
}

.hero-title {
    font-size: 3.5rem;
    font-weight: 700;
    margin-bottom: 1.5rem;
    line-height: 1.2;
    text-shadow: 2px 2px 8px rgba(0, 0, 0, 0.3);
    color: #ffffff;
}

.highlight {
    background: linear-gradient(45deg, #ffd89b, #19547b);
    -webkit-background-clip: text;
    -webkit-text-fill-color: transparent;
    background-clip: text;
    text-shadow: none;
    /* 为不支持background-clip的浏览器提供备用颜色 */
    color: #ffd89b;
}

.hero-subtitle {
    font-size: 1.2rem;
    margin-bottom: 2rem;
    opacity: 1;
    line-height: 1.6;
    text-shadow: 1px 1px 6px rgba(0, 0, 0, 0.4);
    color: #ffffff;
    font-weight: 500;
}

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

.btn {
    padding: 12px 24px;
    border: none;
    border-radius: var(--border-radius);
    font-size: 1rem;
    font-weight: 600;
    cursor: pointer;
    transition: var(--transition);
    display: flex;
    align-items: center;
    gap: 8px;
    text-decoration: none;
}

.btn-primary {
    background: linear-gradient(135deg, #ff9a9e 0%, #fecfef 100%);
    color: white;
    text-shadow: 1px 1px 2px rgba(0, 0, 0, 0.2);
    font-weight: 600;
}

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

.btn-secondary {
    background: rgba(255, 255, 255, 0.2);
    color: white;
    border: 2px solid rgba(255, 255, 255, 0.5);
    text-shadow: 1px 1px 2px rgba(0, 0, 0, 0.3);
    font-weight: 600;
}

.btn-secondary:hover {
    background: rgba(255, 255, 255, 0.3);
    transform: translateY(-2px);
}

/* 英雄视觉效果 */
.hero-visual {
    position: relative;
    height: 500px;
}

.floating-elements {
    position: absolute;
    width: 100%;
    height: 100%;
}

.math-symbol {
    position: absolute;
    font-size: 2rem;
    color: rgba(255, 255, 255, 0.6);
    font-weight: bold;
    animation: float 3s ease-in-out infinite;
    text-shadow: 1px 1px 3px rgba(0, 0, 0, 0.3);
}

.math-symbol:nth-child(1) { top: 10%; left: 10%; animation-delay: 0s; }
.math-symbol:nth-child(2) { top: 20%; right: 20%; animation-delay: 0.5s; }
.math-symbol:nth-child(3) { top: 60%; left: 5%; animation-delay: 1s; }
.math-symbol:nth-child(4) { bottom: 30%; right: 10%; animation-delay: 1.5s; }
.math-symbol:nth-child(5) { top: 40%; left: 50%; animation-delay: 2s; }
.math-symbol:nth-child(6) { bottom: 10%; left: 30%; animation-delay: 2.5s; }

@keyframes float {
    0%, 100% { transform: translateY(0px); }
    50% { transform: translateY(-20px); }
}

.phone-mockup {
    position: absolute;
    top: 50%;
    left: 50%;
    transform: translate(-50%, -50%);
    width: 300px;
    height: 600px;
    background: white;
    border-radius: 30px;
    padding: 20px;
    box-shadow: var(--shadow-hover);
    animation: phoneFloat 4s ease-in-out infinite;
}

@keyframes phoneFloat {
    0%, 100% { transform: translate(-50%, -50%) rotateY(0deg); }
    50% { transform: translate(-50%, -50%) rotateY(5deg); }
}

.phone-screen {
    width: 100%;
    height: 100%;
    background: linear-gradient(135deg, #667eea 0%, #764ba2 100%);
    border-radius: 20px;
    padding: 20px;
    display: flex;
    align-items: center;
    justify-content: center;
}

.app-interface {
    color: white;
    text-align: center;
}

.math-problem {
    font-size: 1.5rem;
    font-weight: bold;
    margin-bottom: 20px;
    padding: 15px;
    background: rgba(255, 255, 255, 0.2);
    border-radius: 10px;
}

.solution-steps {
    text-align: left;
}

.step {
    margin-bottom: 10px;
    padding: 10px;
    background: rgba(255, 255, 255, 0.1);
    border-radius: 8px;
    font-size: 0.9rem;
}

/* 波浪效果 */
.wave-container {
    position: absolute;
    bottom: 0;
    left: 0;
    width: 100%;
    overflow: hidden;
    line-height: 0;
}

.wave {
    position: relative;
    display: block;
    width: calc(100% + 1.3px);
    height: 120px;
}

.shape-fill {
    fill: white;
}

/* 功能特色区域 */
.features {
    padding: 100px 0;
    background: var(--bg-light);
}

.section-header {
    text-align: center;
    margin-bottom: 4rem;
}

.section-title {
    font-size: 2.5rem;
    font-weight: 700;
    margin-bottom: 1rem;
    background: var(--primary-gradient);
    -webkit-background-clip: text;
    -webkit-text-fill-color: transparent;
    background-clip: text;
}

.section-subtitle {
    font-size: 1.2rem;
    color: var(--text-light);
}

.features-grid {
    display: grid;
    grid-template-columns: repeat(auto-fit, minmax(350px, 1fr));
    gap: 2rem;
}

.feature-card {
    background: white;
    padding: 2.5rem;
    border-radius: var(--border-radius);
    text-align: center;
    box-shadow: var(--shadow);
    transition: var(--transition);
    position: relative;
    overflow: hidden;
}

.feature-card:hover {
    transform: translateY(-10px);
    box-shadow: var(--shadow-hover);
}

.feature-card::before {
    content: '';
    position: absolute;
    top: 0;
    left: 0;
    width: 100%;
    height: 4px;
    background: var(--primary-gradient);
    transform: scaleX(0);
    transition: var(--transition);
}

.feature-card:hover::before {
    transform: scaleX(1);
}

.feature-icon {
    width: 80px;
    height: 80px;
    margin: 0 auto 1.5rem;
    background: var(--primary-gradient);
    border-radius: 50%;
    display: flex;
    align-items: center;
    justify-content: center;
    font-size: 2rem;
    color: white;
}

.feature-card h3 {
    font-size: 1.5rem;
    font-weight: 600;
    margin-bottom: 1rem;
    color: var(--text-dark);
}

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

/* 年级适配区域 */
.grades {
    padding: 100px 0;
}

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

.grade-card {
    background: white;
    padding: 2.5rem;
    border-radius: var(--border-radius);
    text-align: center;
    box-shadow: var(--shadow);
    transition: var(--transition);
    position: relative;
    overflow: hidden;
}

.grade-card::before {
    content: '';
    position: absolute;
    top: 0;
    left: 0;
    width: 100%;
    height: 100%;
    opacity: 0;
    transition: var(--transition);
}

.elementary::before {
    background: linear-gradient(135deg, #a8edea 0%, #fed6e3 100%);
}

.middle::before {
    background: linear-gradient(135deg, #ffecd2 0%, #fcb69f 100%);
}

.high::before {
    background: linear-gradient(135deg, #667eea 0%, #764ba2 100%);
}

.grade-card:hover::before {
    opacity: 0.1;
}

.grade-card:hover {
    transform: translateY(-10px) scale(1.02);
    box-shadow: var(--shadow-hover);
}

.grade-icon {
    width: 100px;
    height: 100px;
    margin: 0 auto 1.5rem;
    border-radius: 50%;
    display: flex;
    align-items: center;
    justify-content: center;
    font-size: 2.5rem;
    position: relative;
    z-index: 1;
}

.elementary .grade-icon {
    background: linear-gradient(135deg, #a8edea 0%, #fed6e3 100%);
    color: #2d3748;
}

.middle .grade-icon {
    background: linear-gradient(135deg, #ffecd2 0%, #fcb69f 100%);
    color: #2d3748;
}

.high .grade-icon {
    background: linear-gradient(135deg, #667eea 0%, #764ba2 100%);
    color: white;
}

.grade-card h3 {
    font-size: 1.8rem;
    font-weight: 600;
    margin-bottom: 1.5rem;
    position: relative;
    z-index: 1;
}

.grade-features {
    display: flex;
    flex-wrap: wrap;
    gap: 0.5rem;
    justify-content: center;
    margin-bottom: 1.5rem;
    position: relative;
    z-index: 1;
}

.grade-features span {
    background: var(--bg-light);
    color: var(--text-dark);
    padding: 0.5rem 1rem;
    border-radius: 20px;
    font-size: 0.9rem;
    font-weight: 500;
}

.grade-card p {
    color: var(--text-light);
    font-size: 1.1rem;
    position: relative;
    z-index: 1;
}

/* 统计数据区域 */
.stats {
    padding: 80px 0;
    background: var(--primary-gradient);
    color: white;
}

.stats-grid {
    display: grid;
    grid-template-columns: repeat(auto-fit, minmax(200px, 1fr));
    gap: 2rem;
    text-align: center;
}

.stat-item {
    padding: 2rem;
}

.stat-number {
    font-size: 3rem;
    font-weight: 700;
    margin-bottom: 0.5rem;
    display: block;
}

.stat-label {
    font-size: 1.1rem;
    opacity: 0.9;
}

/* 下载区域 */
.download {
    padding: 100px 0;
    background: var(--bg-light);
    text-align: center;
}

.download-title {
    font-size: 2.5rem;
    font-weight: 700;
    margin-bottom: 1rem;
    background: var(--primary-gradient);
    -webkit-background-clip: text;
    -webkit-text-fill-color: transparent;
    background-clip: text;
}

.download-subtitle {
    font-size: 1.2rem;
    color: var(--text-light);
    margin-bottom: 3rem;
}

.download-buttons {
    display: flex;
    justify-content: center;
    gap: 2rem;
    flex-wrap: wrap;
}

.download-btn {
    display: flex;
    align-items: center;
    gap: 1rem;
    padding: 1rem 2rem;
    background: var(--text-dark);
    color: white;
    text-decoration: none;
    border-radius: var(--border-radius);
    transition: var(--transition);
    min-width: 200px;
}

.download-btn:hover {
    transform: translateY(-3px);
    box-shadow: var(--shadow-hover);
}

.download-btn i {
    font-size: 2rem;
}

.download-btn div {
    text-align: left;
}

.download-btn small {
    display: block;
    font-size: 0.8rem;
    opacity: 0.8;
}

.download-btn strong {
    font-size: 1.1rem;
}

/* 页脚 */
.footer {
    background: var(--text-dark);
    color: white;
    padding: 60px 0 20px;
}

.footer-content {
    display: grid;
    grid-template-columns: repeat(auto-fit, minmax(250px, 1fr));
    gap: 3rem;
    margin-bottom: 3rem;
}

.footer-logo {
    display: flex;
    align-items: center;
    font-size: 1.5rem;
    font-weight: 700;
    margin-bottom: 1rem;
}

.footer-logo i {
    margin-right: 8px;
    color: var(--primary-color);
}

.footer-section h4 {
    margin-bottom: 1.5rem;
    font-size: 1.2rem;
}

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

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

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

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

.social-links {
    display: flex;
    gap: 1rem;
    margin-top: 1.5rem;
}

.social-links a {
    width: 40px;
    height: 40px;
    background: var(--primary-gradient);
    border-radius: 50%;
    display: flex;
    align-items: center;
    justify-content: center;
    color: white;
    text-decoration: none;
    transition: var(--transition);
}

.social-links a:hover {
    transform: translateY(-3px);
    box-shadow: var(--shadow);
}

.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);
}

/* 响应式设计 */
@media (max-width: 768px) {
    .hamburger {
        display: flex;
    }
    
    .nav-menu {
        position: fixed;
        left: -100%;
        top: 70px;
        flex-direction: column;
        background-color: white;
        width: 100%;
        text-align: center;
        transition: 0.3s;
        box-shadow: var(--shadow);
        padding: 2rem 0;
    }
    
    .nav-menu.active {
        left: 0;
    }
    
    .hero-container {
        grid-template-columns: 1fr;
        text-align: center;
        gap: 2rem;
    }
    
    .hero-title {
        font-size: 2.5rem;
    }
    
    .hero-buttons {
        justify-content: center;
        flex-wrap: wrap;
    }
    
    .phone-mockup {
        width: 250px;
        height: 500px;
    }
    
    .features-grid {
        grid-template-columns: 1fr;
    }
    
    .grades-container {
        grid-template-columns: 1fr;
    }
    
    .stats-grid {
        grid-template-columns: repeat(2, 1fr);
    }
    
    .download-buttons {
        flex-direction: column;
        align-items: center;
    }
    
    .footer-content {
        grid-template-columns: 1fr;
        text-align: center;
    }
}

@media (max-width: 480px) {
    .hero-title {
        font-size: 2rem;
    }
    
    .section-title {
        font-size: 2rem;
    }
    
    .stats-grid {
        grid-template-columns: 1fr;
    }
    
    .stat-number {
        font-size: 2.5rem;
    }
}

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

.animate-on-scroll {
    opacity: 0;
    transform: translateY(30px);
    transition: all 0.6s ease;
}

.animate-on-scroll.animated {
    opacity: 1;
    transform: translateY(0);
}

/* 功能特色区域 */
.features {
    padding: 100px 0;
    background: var(--bg-light);
}

.section-header {
    text-align: center;
    margin-bottom: 4rem;
}

.section-title {
    font-size: 2.5rem;
    font-weight: 700;
    margin-bottom: 1rem;
    background: var(--primary-gradient);
    -webkit-background-clip: text;
    -webkit-text-fill-color: transparent;
    background-clip: text;
}

.section-subtitle {
    font-size: 1.2rem;
    color: var(--text-light);
}

.features-grid {
    display: grid;
    grid-template-columns: repeat(auto-fit, minmax(350px, 1fr));
    gap: 2rem;
}

.feature-card {
    background: white;
    padding: 2.5rem;
    border-radius: var(--border-radius);
    text-align: center;
    box-shadow: var(--shadow);
    transition: var(--transition);
    position: relative;
    overflow: hidden;
}

.feature-card:hover {
    transform: translateY(-10px);
    box-shadow: var(--shadow-hover);
}

.feature-card::before {
    content: '';
    position: absolute;
    top: 0;
    left: 0;
    width: 100%;
    height: 4px;
    background: var(--primary-gradient);
    transform: scaleX(0);
    transition: var(--transition);
}

.feature-card:hover::before {
    transform: scaleX(1);
}

.feature-icon {
    width: 80px;
    height: 80px;
    margin: 0 auto 1.5rem;
    background: var(--primary-gradient);
    border-radius: 50%;
    display: flex;
    align-items: center;
    justify-content: center;
    font-size: 2rem;
    color: white;
}

.feature-card h3 {
    font-size: 1.5rem;
    font-weight: 600;
    margin-bottom: 1rem;
    color: var(--text-dark);
}

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

/* 年级适配区域 */
.grades {
    padding: 100px 0;
}

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

.grade-card {
    background: white;
    padding: 2.5rem;
    border-radius: var(--border-radius);
    text-align: center;
    box-shadow: var(--shadow);
    transition: var(--transition);
    position: relative;
    overflow: hidden;
}

.grade-card::before {
    content: '';
    position: absolute;
    top: 0;
    left: 0;
    width: 100%;
    height: 100%;
    opacity: 0;
    transition: var(--transition);
}

.elementary::before {
    background: linear-gradient(135deg, #a8edea 0%, #fed6e3 100%);
}

.middle::before {
    background: linear-gradient(135deg, #ffecd2 0%, #fcb69f 100%);
}

.high::before {
    background: linear-gradient(135deg, #667eea 0%, #764ba2 100%);
}

.grade-card:hover::before {
    opacity: 0.1;
}

.grade-card:hover {
    transform: translateY(-10px) scale(1.02);
    box-shadow: var(--shadow-hover);
}

.grade-icon {
    width: 100px;
    height: 100px;
    margin: 0 auto 1.5rem;
    border-radius: 50%;
    display: flex;
    align-items: center;
    justify-content: center;
    font-size: 2.5rem;
    position: relative;
    z-index: 1;
}

.elementary .grade-icon {
    background: linear-gradient(135deg, #a8edea 0%, #fed6e3 100%);
    color: #2d3748;
}

.middle .grade-icon {
    background: linear-gradient(135deg, #ffecd2 0%, #fcb69f 100%);
    color: #2d3748;
}

.high .grade-icon {
    background: linear-gradient(135deg, #667eea 0%, #764ba2 100%);
    color: white;
}

.grade-card h3 {
    font-size: 1.8rem;
    font-weight: 600;
    margin-bottom: 1.5rem;
    position: relative;
    z-index: 1;
}

.grade-features {
    display: flex;
    flex-wrap: wrap;
    gap: 0.5rem;
    justify-content: center;
    margin-bottom: 1.5rem;
    position: relative;
    z-index: 1;
}

.grade-features span {
    background: var(--bg-light);
    color: var(--text-dark);
    padding: 0.5rem 1rem;
    border-radius: 20px;
    font-size: 0.9rem;
    font-weight: 500;
}

.grade-card p {
    color: var(--text-light);
    font-size: 1.1rem;
    position: relative;
    z-index: 1;
}

/* 统计数据区域 */
.stats {
    padding: 80px 0;
    background: var(--primary-gradient);
    color: white;
}

.stats-grid {
    display: grid;
    grid-template-columns: repeat(auto-fit, minmax(200px, 1fr));
    gap: 2rem;
    text-align: center;
}

.stat-item {
    padding: 2rem;
}

.stat-number {
    font-size: 3rem;
    font-weight: 700;
    margin-bottom: 0.5rem;
    display: block;
}

.stat-label {
    font-size: 1.1rem;
    opacity: 0.9;
}

/* 下载区域 */
.download {
    padding: 100px 0;
    background: var(--bg-light);
    text-align: center;
}

.download-title {
    font-size: 2.5rem;
    font-weight: 700;
    margin-bottom: 1rem;
    background: var(--primary-gradient);
    -webkit-background-clip: text;
    -webkit-text-fill-color: transparent;
    background-clip: text;
}

.download-subtitle {
    font-size: 1.2rem;
    color: var(--text-light);
    margin-bottom: 3rem;
}

.download-buttons {
    display: flex;
    justify-content: center;
    gap: 2rem;
    flex-wrap: wrap;
}

.download-btn {
    display: flex;
    align-items: center;
    gap: 1rem;
    padding: 1rem 2rem;
    background: var(--text-dark);
    color: white;
    text-decoration: none;
    border-radius: var(--border-radius);
    transition: var(--transition);
    min-width: 200px;
}

.download-btn:hover {
    transform: translateY(-3px);
    box-shadow: var(--shadow-hover);
}

.download-btn i {
    font-size: 2rem;
}

.download-btn div {
    text-align: left;
}

.download-btn small {
    display: block;
    font-size: 0.8rem;
    opacity: 0.8;
}

.download-btn strong {
    font-size: 1.1rem;
}

/* 页脚 */
.footer {
    background: var(--text-dark);
    color: white;
    padding: 60px 0 20px;
}

.footer-content {
    display: grid;
    grid-template-columns: repeat(auto-fit, minmax(250px, 1fr));
    gap: 3rem;
    margin-bottom: 3rem;
}

.footer-logo {
    display: flex;
    align-items: center;
    font-size: 1.5rem;
    font-weight: 700;
    margin-bottom: 1rem;
}

.footer-logo i {
    margin-right: 8px;
    color: var(--primary-color);
}

.footer-section h4 {
    margin-bottom: 1.5rem;
    font-size: 1.2rem;
}

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

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

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

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

.social-links {
    display: flex;
    gap: 1rem;
    margin-top: 1.5rem;
}

.social-links a {
    width: 40px;
    height: 40px;
    background: var(--primary-gradient);
    border-radius: 50%;
    display: flex;
    align-items: center;
    justify-content: center;
    color: white;
    text-decoration: none;
    transition: var(--transition);
}

.social-links a:hover {
    transform: translateY(-3px);
    box-shadow: var(--shadow);
}

.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);
}

/* 响应式设计 */
@media (max-width: 768px) {
    .hamburger {
        display: flex;
    }
    
    .nav-menu {
        position: fixed;
        left: -100%;
        top: 70px;
        flex-direction: column;
        background-color: white;
        width: 100%;
        text-align: center;
        transition: 0.3s;
        box-shadow: var(--shadow);
        padding: 2rem 0;
    }
    
    .nav-menu.active {
        left: 0;
    }
    
    .hero-container {
        grid-template-columns: 1fr;
        text-align: center;
        gap: 2rem;
    }
    
    .hero-title {
        font-size: 2.5rem;
    }
    
    .hero-buttons {
        justify-content: center;
        flex-wrap: wrap;
    }
    
    .phone-mockup {
        width: 250px;
        height: 500px;
    }
    
    .features-grid {
        grid-template-columns: 1fr;
    }
    
    .grades-container {
        grid-template-columns: 1fr;
    }
    
    .stats-grid {
        grid-template-columns: repeat(2, 1fr);
    }
    
    .download-buttons {
        flex-direction: column;
        align-items: center;
    }
    
    .footer-content {
        grid-template-columns: 1fr;
        text-align: center;
    }
}

@media (max-width: 480px) {
    .hero-title {
        font-size: 2rem;
    }
    
    .section-title {
        font-size: 2rem;
    }
    
    .stats-grid {
        grid-template-columns: 1fr;
    }
    
    .stat-number {
        font-size: 2.5rem;
    }
}

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

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

@keyframes fadeInRight {
    from {
        opacity: 0;
        transform: translateX(30px);
    }
    to {
        opacity: 1;
        transform: translateX(0);
    }
}

.animate-on-scroll {
    opacity: 0;
    transform: translateY(30px);
    transition: all 0.6s ease;
}

.animate-on-scroll.animated {
    opacity: 1;
    transform: translateY(0);
}

/* 加载动画 */
.loading {
    display: inline-block;
    width: 20px;
    height: 20px;
    border: 3px solid rgba(255, 255, 255, 0.3);
    border-radius: 50%;
    border-top-color: white;
    animation: spin 1s ease-in-out infinite;
}

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

/* AI智能元素样式 */

/* AI浮动符号 */
.ai-symbol {
    position: absolute;
    font-size: 1.8rem;
    color: rgba(255, 255, 255, 0.7);
    animation: aiFloat 4s ease-in-out infinite;
    text-shadow: 1px 1px 3px rgba(0, 0, 0, 0.3);
}

.ai-symbol:nth-child(7) { top: 15%; right: 15%; animation-delay: 0.3s; }
.ai-symbol:nth-child(8) { top: 70%; left: 15%; animation-delay: 1.3s; }
.ai-symbol:nth-child(9) { bottom: 20%; right: 25%; animation-delay: 2.3s; }
.ai-symbol:nth-child(10) { top: 35%; right: 5%; animation-delay: 3.3s; }

@keyframes aiFloat {
    0%, 100% { transform: translateY(0px) rotate(0deg); }
    25% { transform: translateY(-15px) rotate(5deg); }
    50% { transform: translateY(-10px) rotate(-3deg); }
    75% { transform: translateY(-20px) rotate(3deg); }
}

/* AI徽章 */
.ai-badge {
    position: absolute;
    top: -6px;
    right: -6px;
    background: linear-gradient(135deg, #00ff88 0%, #00d4ff 70%, #090979 100%);
    color: white;
    font-size: 0.65rem;
    font-weight: 700;
    padding: 6px 10px;
    border-radius: 20px;
    box-shadow: 
        0 4px 12px rgba(0, 212, 255, 0.3),
        0 2px 4px rgba(0, 0, 0, 0.1),
        inset 0 1px 0 rgba(255, 255, 255, 0.2);
    border: 1.5px solid rgba(255, 255, 255, 0.3);
    backdrop-filter: blur(8px);
    animation: aiPulse 3s ease-in-out infinite;
    z-index: 10;
    letter-spacing: 0.5px;
    text-transform: uppercase;
    font-family: -apple-system, BlinkMacSystemFont, 'Segoe UI', sans-serif;
}

.ai-badge::before {
    content: '';
    position: absolute;
    top: -1px;
    left: -1px;
    right: -1px;
    bottom: -1px;
    background: linear-gradient(45deg, #00ff88, #00d4ff, #090979, #00ff88);
    border-radius: 20px;
    z-index: -1;
    opacity: 0;
    animation: borderGlow 3s ease-in-out infinite;
}

.ai-badge::after {
    content: '✨';
    position: absolute;
    top: -2px;
    right: -2px;
    font-size: 0.6rem;
    animation: sparkle 2s ease-in-out infinite;
}

@keyframes aiPulse {
    0%, 100% { 
        transform: scale(1); 
        box-shadow: 
            0 4px 12px rgba(0, 212, 255, 0.3),
            0 2px 4px rgba(0, 0, 0, 0.1),
            inset 0 1px 0 rgba(255, 255, 255, 0.2);
    }
    50% { 
        transform: scale(1.05); 
        box-shadow: 
            0 6px 20px rgba(0, 212, 255, 0.5),
            0 3px 8px rgba(0, 255, 136, 0.3),
            inset 0 1px 0 rgba(255, 255, 255, 0.4);
    }
}

@keyframes borderGlow {
    0%, 100% { opacity: 0; }
    50% { opacity: 0.6; }
}

@keyframes sparkle {
    0%, 100% { 
        opacity: 0; 
        transform: rotate(0deg) scale(0.8); 
    }
    50% { 
        opacity: 1; 
        transform: rotate(180deg) scale(1.2); 
    }
}

/* AI核心区域 */
.ai-core {
    padding: 100px 0;
    background: linear-gradient(135deg, #667eea 0%, #764ba2 100%);
    color: white;
    position: relative;
    overflow: hidden;
}

.ai-core .section-title {
    color: white !important;
    text-shadow: 2px 2px 8px rgba(0, 0, 0, 0.3);
    background: none !important;
    -webkit-text-fill-color: white !important;
}

.ai-core .section-subtitle {
    color: rgba(255, 255, 255, 0.9) !important;
    text-shadow: 1px 1px 6px rgba(0, 0, 0, 0.3);
}

.ai-core::before {
    content: '';
    position: absolute;
    top: 0;
    left: 0;
    right: 0;
    bottom: 0;
    background: url('data:image/svg+xml,<svg xmlns="http://www.w3.org/2000/svg" viewBox="0 0 100 100"><circle cx="20" cy="20" r="2" fill="rgba(255,255,255,0.1)"/><circle cx="80" cy="40" r="1" fill="rgba(255,255,255,0.1)"/><circle cx="40" cy="80" r="1.5" fill="rgba(255,255,255,0.1)"/><circle cx="60" cy="20" r="1" fill="rgba(255,255,255,0.1)"/><circle cx="30" cy="60" r="2" fill="rgba(255,255,255,0.1)"/></svg>');
    opacity: 0.3;
}

.ai-brain-icon {
    color: #00d4ff;
    margin-right: 10px;
    animation: brainPulse 3s ease-in-out infinite;
}

@keyframes brainPulse {
    0%, 100% { transform: scale(1); }
    50% { transform: scale(1.1); }
}

.ai-features-container {
    display: grid;
    grid-template-columns: 1fr 1fr;
    gap: 4rem;
    margin-top: 4rem;
    position: relative;
    z-index: 1;
}

/* AI聊天演示 */
.ai-feature-main {
    display: flex;
    justify-content: center;
    align-items: center;
}

.ai-chat-demo {
    background: rgba(255, 255, 255, 0.1);
    backdrop-filter: blur(10px);
    border-radius: 16px;
    padding: 0;
    width: 100%;
    max-width: 400px;
    box-shadow: 0 20px 40px rgba(0, 0, 0, 0.2);
    border: 1px solid rgba(255, 255, 255, 0.2);
    animation: chatAppear 4s ease-in-out infinite;
}

@keyframes chatAppear {
    0%, 100% {
        opacity: 0.9;
        transform: scale(0.95) translateY(10px);
    }
    50% {
        opacity: 1;
        transform: scale(1) translateY(0);
    }
}

.chat-header {
    padding: 1.5rem;
    border-bottom: 1px solid rgba(255, 255, 255, 0.1);
    display: flex;
    align-items: center;
    gap: 1rem;
    animation: headerSlide 3s ease-in-out infinite;
}

@keyframes headerSlide {
    0%, 100% {
        opacity: 0.9;
        transform: translateX(-10px);
    }
    50% {
        opacity: 1;
        transform: translateX(0);
    }
}

.ai-avatar {
    width: 50px;
    height: 50px;
    background: linear-gradient(135deg, #00d4ff 0%, #090979 100%);
    border-radius: 50%;
    display: flex;
    align-items: center;
    justify-content: center;
    font-size: 1.5rem;
    color: white;
    animation: avatarGlow 2s ease-in-out infinite;
    position: relative;
    overflow: hidden;
}

.ai-avatar::before {
    content: '';
    position: absolute;
    top: -50%;
    left: -50%;
    width: 200%;
    height: 200%;
    background: linear-gradient(45deg, transparent, rgba(255, 255, 255, 0.3), transparent);
    animation: avatarShine 3s linear infinite;
}

@keyframes avatarShine {
    0% { transform: rotate(0deg); }
    100% { transform: rotate(360deg); }
}

@keyframes avatarGlow {
    0%, 100% { 
        box-shadow: 0 0 20px rgba(0, 212, 255, 0.3);
        transform: scale(1);
    }
    50% { 
        box-shadow: 0 0 30px rgba(0, 212, 255, 0.6);
        transform: scale(1.05);
    }
}

.ai-avatar i {
    position: relative;
    z-index: 1;
    animation: robotBlink 4s ease-in-out infinite;
}

@keyframes robotBlink {
    0%, 90%, 100% { opacity: 1; }
    95% { opacity: 0.3; }
}

.ai-info h4 {
    margin: 0;
    font-size: 1.1rem;
    animation: nameTypewriter 4s ease-in-out infinite;
    color: #ffffff;
    text-shadow: 1px 1px 3px rgba(0, 0, 0, 0.3);
}

@keyframes nameTypewriter {
    0%, 100% { 
        opacity: 0.8; 
        transform: scaleX(0.95);
    }
    50% { 
        opacity: 1; 
        transform: scaleX(1);
    }
}

.ai-status {
    font-size: 0.9rem;
    opacity: 0.9;
    display: flex;
    align-items: center;
    gap: 5px;
    animation: statusFade 3s ease-in-out infinite;
    color: rgba(255, 255, 255, 0.9);
    text-shadow: 1px 1px 2px rgba(0, 0, 0, 0.3);
}

@keyframes statusFade {
    0%, 100% { 
        opacity: 0.6; 
        transform: translateY(5px); 
    }
    50% { 
        opacity: 0.9; 
        transform: translateY(0); 
    }
}

.ai-status i {
    color: #00ff88;
    animation: statusBlink 2s ease-in-out infinite;
}

@keyframes statusBlink {
    0%, 100% { 
        opacity: 1; 
        transform: scale(1);
    }
    50% { 
        opacity: 0.3; 
        transform: scale(1.2);
    }
}

.chat-messages {
    padding: 1.5rem;
    min-height: 400px;
    overflow: visible;
}

.message {
    margin-bottom: 1rem;
    opacity: 0.9;
    transform: translateY(10px);
    animation: messageSlide 2s ease-in-out infinite;
}

.message:nth-child(1) { animation-delay: 0s; }
.message:nth-child(2) { animation-delay: 0.3s; }
.message:nth-child(3) { animation-delay: 0.6s; }
.message:nth-child(4) { animation-delay: 0.9s; }

@keyframes messageSlide {
    0%, 100% { 
        opacity: 0.9; 
        transform: translateY(10px) scale(0.98); 
    }
    50% { 
        opacity: 1; 
        transform: translateY(-2px) scale(1.01); 
    }
}

.message-content {
    padding: 12px 16px;
    border-radius: 12px;
    display: flex;
    align-items: flex-start;
    gap: 8px;
    line-height: 1.4;
    position: relative;
    overflow: hidden;
    color: #ffffff;
    text-shadow: 1px 1px 2px rgba(0, 0, 0, 0.2);
}

.ai-message .message-content {
    background: rgba(0, 212, 255, 0.2);
    border: 1px solid rgba(0, 212, 255, 0.3);
    animation: aiMessageGlow 3s ease-in-out infinite;
}

@keyframes aiMessageGlow {
    0%, 100% { 
        box-shadow: 0 0 10px rgba(0, 212, 255, 0.2);
    }
    50% { 
        box-shadow: 0 0 20px rgba(0, 212, 255, 0.4);
    }
}

.ai-message .message-content::before {
    content: '';
    position: absolute;
    top: 0;
    left: -100%;
    width: 100%;
    height: 100%;
    background: linear-gradient(90deg, transparent, rgba(255, 255, 255, 0.2), transparent);
    animation: messageShimmer 4s linear infinite;
}

@keyframes messageShimmer {
    0% { left: -100%; }
    100% { left: 100%; }
}

.user-message .message-content {
    background: rgba(255, 255, 255, 0.1);
    border: 1px solid rgba(255, 255, 255, 0.2);
    margin-left: auto;
    max-width: 80%;
    animation: userMessagePop 1.5s ease-in-out infinite;
}

@keyframes userMessagePop {
    0%, 100% { 
        transform: scale(0.95) rotate(-1deg); 
        opacity: 0.9; 
    }
    50% { 
        transform: scale(1.02) rotate(0.5deg); 
        opacity: 1; 
    }
}

.message-icon {
    color: #00d4ff;
    margin-top: 2px;
    flex-shrink: 0;
    animation: iconSpin 3s ease-in-out infinite;
}

@keyframes iconSpin {
    0%, 100% { transform: rotate(0deg) scale(1); }
    25% { transform: rotate(5deg) scale(1.1); }
    50% { transform: rotate(0deg) scale(1); }
    75% { transform: rotate(-5deg) scale(1.1); }
}

.typing-indicator {
    display: flex;
    gap: 4px;
    padding: 12px 16px;
    background: rgba(0, 212, 255, 0.2);
    border-radius: 12px;
    width: fit-content;
    animation: typingAppear 2s ease-in-out infinite;
}

@keyframes typingAppear {
    0%, 100% { 
        opacity: 0.8; 
        transform: scale(0.95); 
    }
    50% { 
        opacity: 1; 
        transform: scale(1.05); 
    }
}

.typing-indicator span {
    width: 8px;
    height: 8px;
    background: #00d4ff;
    border-radius: 50%;
    animation: typingDot 1.4s ease-in-out infinite;
}

.typing-indicator span:nth-child(2) { animation-delay: 0.2s; }
.typing-indicator span:nth-child(3) { animation-delay: 0.4s; }

@keyframes typingDot {
    0%, 60%, 100% { 
        transform: translateY(0) scale(1); 
        background: #00d4ff;
    }
    30% { 
        transform: translateY(-10px) scale(1.2); 
        background: #00ff88;
    }
}

/* AI能力展示 */
.ai-capabilities {
    display: grid;
    grid-template-columns: 1fr 1fr;
    gap: 2rem;
}

.ai-capability {
    background: rgba(255, 255, 255, 0.1);
    padding: 2rem;
    border-radius: 12px;
    text-align: center;
    backdrop-filter: blur(10px);
    border: 1px solid rgba(255, 255, 255, 0.1);
    transition: var(--transition);
}

.ai-capability:hover {
    transform: translateY(-5px);
    background: rgba(255, 255, 255, 0.15);
}

.capability-icon {
    width: 60px;
    height: 60px;
    background: linear-gradient(135deg, #00d4ff 0%, #090979 100%);
    border-radius: 50%;
    display: flex;
    align-items: center;
    justify-content: center;
    margin: 0 auto 1rem;
    font-size: 1.5rem;
    color: white;
}

.ai-capability h4 {
    margin-bottom: 1rem;
    font-size: 1.2rem;
    color: white;
    text-shadow: 1px 1px 3px rgba(0, 0, 0, 0.3);
}

.ai-capability p {
    margin-bottom: 1rem;
    opacity: 0.9;
    line-height: 1.5;
    color: rgba(255, 255, 255, 0.9);
    text-shadow: 1px 1px 2px rgba(0, 0, 0, 0.2);
}

.capability-stats {
    display: flex;
    justify-content: center;
}

.stat {
    background: linear-gradient(135deg, #00ff88 0%, #00d4ff 100%);
    color: white;
    padding: 0.5rem 1rem;
    border-radius: 20px;
    font-size: 0.9rem;
    font-weight: 600;
}

/* AI学习路径 */
.ai-learning-path {
    margin-top: 4rem;
    position: relative;
    z-index: 1;
}

.path-title {
    text-align: center;
    font-size: 2rem;
    margin-bottom: 3rem;
    display: flex;
    align-items: center;
    justify-content: center;
    gap: 10px;
    color: white;
    text-shadow: 2px 2px 6px rgba(0, 0, 0, 0.3);
}

.path-title i {
    color: #00d4ff;
}

.learning-steps {
    display: flex;
    justify-content: space-between;
    align-items: center;
    max-width: 800px;
    margin: 0 auto;
    position: relative;
}

.step-item {
    text-align: center;
    position: relative;
    flex: 1;
}

.step-number {
    width: 60px;
    height: 60px;
    background: linear-gradient(135deg, #00d4ff 0%, #090979 100%);
    border-radius: 50%;
    display: flex;
    align-items: center;
    justify-content: center;
    font-size: 1.5rem;
    font-weight: bold;
    margin: 0 auto 1rem;
    box-shadow: 0 10px 20px rgba(0, 212, 255, 0.3);
    animation: stepPulse 3s ease-in-out infinite;
}

.step-item:nth-child(1) .step-number { animation-delay: 0s; }
.step-item:nth-child(2) .step-number { animation-delay: 0.5s; }
.step-item:nth-child(3) .step-number { animation-delay: 1s; }
.step-item:nth-child(4) .step-number { animation-delay: 1.5s; }

@keyframes stepPulse {
    0%, 100% { transform: scale(1); }
    50% { transform: scale(1.05); }
}

.step-content h4 {
    margin-bottom: 0.5rem;
    font-size: 1.1rem;
    color: white;
    text-shadow: 1px 1px 3px rgba(0, 0, 0, 0.3);
}

.step-content p {
    opacity: 0.9;
    font-size: 0.9rem;
    color: rgba(255, 255, 255, 0.9);
    text-shadow: 1px 1px 2px rgba(0, 0, 0, 0.2);
}

.step-connector {
    position: absolute;
    top: 30px;
    left: 60%;
    width: 80%;
    height: 2px;
    background: linear-gradient(90deg, #00d4ff 0%, #090979 100%);
    opacity: 0.6;
}

.step-item:last-child .step-connector {
    display: none;
}

/* 手机界面AI元素 */
.ai-header {
    background: rgba(0, 212, 255, 0.2);
    padding: 8px 12px;
    border-radius: 8px;
    margin-bottom: 15px;
    display: flex;
    align-items: center;
    gap: 8px;
    font-size: 0.8rem;
    animation: aiThinking 2s ease-in-out infinite;
    border: 1px solid rgba(0, 212, 255, 0.3);
}

@keyframes aiThinking {
    0%, 100% { 
        opacity: 0.8; 
        box-shadow: 0 0 10px rgba(0, 212, 255, 0.2);
    }
    50% { 
        opacity: 1; 
        box-shadow: 0 0 20px rgba(0, 212, 255, 0.4);
    }
}

.ai-header i {
    animation: brainSpin 3s linear infinite;
}

@keyframes brainSpin {
    0% { transform: rotate(0deg) scale(1); }
    25% { transform: rotate(90deg) scale(1.1); }
    50% { transform: rotate(180deg) scale(1); }
    75% { transform: rotate(270deg) scale(1.1); }
    100% { transform: rotate(360deg) scale(1); }
}

.step-icon {
    color: #00d4ff;
    margin-right: 8px;
    font-size: 0.8rem;
    animation: stepIconPulse 2s ease-in-out infinite;
}

@keyframes stepIconPulse {
    0%, 100% { 
        transform: scale(1); 
        opacity: 0.8;
    }
    50% { 
        transform: scale(1.2); 
        opacity: 1;
    }
}

.step {
    opacity: 0.9;
    transform: translateX(-10px);
    animation: stepAppear 2s ease-in-out infinite;
}

.step:nth-child(1) { animation-delay: 0s; }
.step:nth-child(2) { animation-delay: 0.2s; }
.step:nth-child(3) { animation-delay: 0.4s; }

@keyframes stepAppear {
    0%, 100% {
        opacity: 0.9;
        transform: translateX(-10px);
    }
    50% {
        opacity: 1;
        transform: translateX(3px);
    }
}

.math-problem {
    animation: problemHighlight 4s ease-in-out infinite;
    transition: all 0.3s ease;
}

@keyframes problemHighlight {
    0%, 100% { 
        background: rgba(255, 255, 255, 0.2);
        box-shadow: 0 0 15px rgba(255, 255, 255, 0.1);
    }
    50% { 
        background: rgba(255, 255, 255, 0.3);
        box-shadow: 0 0 25px rgba(255, 255, 255, 0.2);
    }
}

.ai-confidence {
    margin-top: 15px;
    padding: 10px;
    background: rgba(0, 212, 255, 0.1);
    border-radius: 8px;
    display: flex;
    align-items: center;
    gap: 10px;
    font-size: 0.8rem;
    border: 1px solid rgba(0, 212, 255, 0.2);
    animation: confidenceGlow 3s ease-in-out infinite;
}

@keyframes confidenceGlow {
    0%, 100% { 
        border-color: rgba(0, 212, 255, 0.2);
        box-shadow: 0 0 10px rgba(0, 212, 255, 0.1);
    }
    50% { 
        border-color: rgba(0, 212, 255, 0.5);
        box-shadow: 0 0 20px rgba(0, 212, 255, 0.3);
    }
}

.confidence-label {
    font-weight: bold;
    color: #00d4ff;
    animation: labelPulse 2s ease-in-out infinite;
}

@keyframes labelPulse {
    0%, 100% { opacity: 0.8; }
    50% { opacity: 1; }
}

.confidence-bar {
    flex: 1;
    height: 6px;
    background: rgba(255, 255, 255, 0.2);
    border-radius: 3px;
    overflow: hidden;
    position: relative;
}

.confidence-bar::before {
    content: '';
    position: absolute;
    top: 0;
    left: -100%;
    width: 100%;
    height: 100%;
    background: linear-gradient(90deg, transparent, rgba(255, 255, 255, 0.3), transparent);
    animation: barShimmer 2s linear infinite;
}

@keyframes barShimmer {
    0% { left: -100%; }
    100% { left: 100%; }
}

.confidence-fill {
    height: 100%;
    width: 0%;
    background: linear-gradient(90deg, #00ff88 0%, #00d4ff 100%);
    border-radius: 3px;
    animation: confidenceFill 4s ease-in-out infinite;
    position: relative;
    overflow: hidden;
}

.confidence-fill::after {
    content: '';
    position: absolute;
    top: 0;
    left: 0;
    width: 100%;
    height: 100%;
    background: linear-gradient(90deg, transparent, rgba(255, 255, 255, 0.6), transparent);
    animation: fillGlow 2s ease-in-out infinite;
}

@keyframes fillGlow {
    0%, 100% { transform: translateX(-100%); }
    50% { transform: translateX(100%); }
}

@keyframes confidenceFill {
    0%, 100% { width: 90%; }
    50% { width: 98.5%; }
}

.confidence-value {
    font-weight: bold;
    color: #00ff88;
    animation: valueCount 4s ease-in-out infinite;
}

@keyframes valueCount {
    0%, 100% { 
        opacity: 0.8; 
        transform: scale(0.95);
    }
    50% { 
        opacity: 1; 
        transform: scale(1.05);
    }
}

/* 响应式设计 - AI元素 */
@media (max-width: 768px) {
    .ai-features-container {
        grid-template-columns: 1fr;
        gap: 2rem;
    }
    
    .ai-capabilities {
        grid-template-columns: 1fr;
    }
    
    .learning-steps {
        flex-direction: column;
        gap: 2rem;
    }
    
    .step-connector {
        display: none;
    }
    
    .ai-chat-demo {
        max-width: 100%;
    }
    
    .ai-symbol {
        font-size: 1.5rem;
    }
}

@media (max-width: 480px) {
    .ai-core {
        padding: 60px 0;
    }
    
    .path-title {
        font-size: 1.5rem;
    }
    
    .step-number {
        width: 50px;
        height: 50px;
        font-size: 1.2rem;
    }
}