/* ============================================
   幼升思维AI出题平台 - 落地页样式
   卡通趣味风格，适配移动端和PC端
   ============================================ */

/* CSS变量 */
:root {
    /* 主色调 - 温暖活泼的教育风格 */
    --primary-color: #FF6B35;
    --primary-dark: #E55A2B;
    --primary-light: #FF8A5C;
    
    /* 辅助色 */
    --secondary-color: #4ECDC4;
    --secondary-dark: #3DB8B0;
    --accent-color: #FFE66D;
    --accent-dark: #FFD93D;
    
    /* 中性色 */
    --text-dark: #2C3E50;
    --text-light: #6C757D;
    --text-white: #FFFFFF;
    --bg-light: #F8F9FA;
    --bg-white: #FFFFFF;
    
    /* 渐变色 */
    --gradient-primary: linear-gradient(135deg, #FF6B35 0%, #FF8A5C 100%);
    --gradient-secondary: linear-gradient(135deg, #4ECDC4 0%, #44B3A8 100%);
    --gradient-hero: linear-gradient(135deg, #667eea 0%, #764ba2 100%);
    
    /* 阴影 */
    --shadow-sm: 0 2px 8px rgba(0, 0, 0, 0.08);
    --shadow-md: 0 4px 16px rgba(0, 0, 0, 0.12);
    --shadow-lg: 0 8px 32px rgba(0, 0, 0, 0.16);
    --shadow-card: 0 10px 40px rgba(255, 107, 53, 0.2);
    
    /* 圆角 */
    --radius-sm: 8px;
    --radius-md: 12px;
    --radius-lg: 20px;
    --radius-full: 50%;
    
    /* 间距 */
    --spacing-xs: 8px;
    --spacing-sm: 16px;
    --spacing-md: 24px;
    --spacing-lg: 40px;
    --spacing-xl: 60px;
    --spacing-xxl: 80px;
    
    /* 字体大小 */
    --font-xs: 0.75rem;
    --font-sm: 0.875rem;
    --font-base: 1rem;
    --font-lg: 1.125rem;
    --font-xl: 1.25rem;
    --font-2xl: 1.5rem;
    --font-3xl: 2rem;
    --font-4xl: 2.5rem;
    --font-5xl: 3rem;
}

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

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

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

a {
    text-decoration: none;
    color: inherit;
}

ul {
    list-style: none;
}

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

/* 容器 */
.container {
    width: 100%;
    max-width: 1200px;
    margin: 0 auto;
    padding: 0 var(--spacing-md);
}

/* ============================================
   导航栏
   ============================================ */
.navbar {
    position: fixed;
    top: 0;
    left: 0;
    right: 0;
    z-index: 1000;
    background: rgba(255, 255, 255, 0.95);
    backdrop-filter: blur(10px);
    box-shadow: var(--shadow-sm);
    transition: all 0.3s ease;
}

.navbar .container {
    display: flex;
    justify-content: space-between;
    align-items: center;
    height: 70px;
}

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

.logo-icon {
    font-size: 2rem;
}

.logo-text {
    font-size: var(--font-xl);
    font-weight: 700;
    color: var(--primary-color);
}

.nav-links {
    display: flex;
    gap: var(--spacing-lg);
}

.nav-links a {
    font-weight: 500;
    color: var(--text-dark);
    transition: color 0.3s ease;
    position: relative;
}

.nav-links a::after {
    content: '';
    position: absolute;
    bottom: -4px;
    left: 0;
    width: 0;
    height: 2px;
    background: var(--primary-color);
    transition: width 0.3s ease;
}

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

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

/* ============================================
   Hero 首屏
   ============================================ */
.hero {
    position: relative;
    min-height: 100vh;
    display: flex;
    align-items: center;
    background: linear-gradient(135deg, #FFF5F0 0%, #FFF0E6 50%, #FFE6D9 100%);
    padding-top: 70px;
    overflow: hidden;
}

.hero .container {
    position: relative;
    z-index: 2;
}

.hero-content {
    display: grid;
    grid-template-columns: 1fr 1fr;
    gap: var(--spacing-xl);
    align-items: center;
}

.hero-text {
    animation: fadeInUp 0.8s ease-out;
}

.hero-text h1 {
    font-size: var(--font-5xl);
    font-weight: 800;
    line-height: 1.2;
    margin-bottom: var(--spacing-md);
    color: var(--text-dark);
}

.hero-text h1 .highlight {
    background: var(--gradient-primary);
    -webkit-background-clip: text;
    -webkit-text-fill-color: transparent;
    background-clip: text;
}

.hero-subtitle {
    font-size: var(--font-lg);
    color: var(--text-light);
    margin-bottom: var(--spacing-lg);
    line-height: 1.8;
}

.hero-stats {
    display: flex;
    gap: var(--spacing-lg);
    margin-bottom: var(--spacing-lg);
}

.stat-item {
    text-align: center;
    padding: var(--spacing-sm) var(--spacing-md);
    background: var(--bg-white);
    border-radius: var(--radius-md);
    box-shadow: var(--shadow-sm);
}

.stat-number {
    display: block;
    font-size: var(--font-3xl);
    font-weight: 800;
    color: var(--primary-color);
}

.stat-label {
    font-size: var(--font-sm);
    color: var(--text-light);
}

/* 下载按钮 */
.download-buttons {
    display: flex;
    gap: var(--spacing-sm);
    flex-wrap: wrap;
}

.download-btn {
    display: inline-flex;
    align-items: center;
    gap: var(--spacing-xs);
    padding: var(--spacing-sm) var(--spacing-md);
    border-radius: var(--radius-md);
    font-weight: 600;
    transition: all 0.3s ease;
    box-shadow: var(--shadow-md);
}

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

.ios-btn {
    background: var(--text-dark);
    color: var(--text-white);
}

.ios-btn:hover {
    background: #1a252f;
}

.android-btn {
    background: var(--secondary-color);
    color: var(--text-white);
}

.android-btn:hover {
    background: var(--secondary-dark);
}

.btn-icon {
    width: 28px;
    height: 28px;
}

.btn-text {
    display: flex;
    flex-direction: column;
    align-items: flex-start;
}

.btn-small {
    font-size: var(--font-xs);
    font-weight: 400;
    opacity: 0.8;
}

.btn-large {
    font-size: var(--font-base);
    font-weight: 600;
}

/* App Mockup */
.hero-image {
    display: flex;
    justify-content: center;
    align-items: center;
    animation: fadeInRight 0.8s ease-out;
}

.app-mockup {
    position: relative;
    width: 280px;
    height: 560px;
    background: #1a1a1a;
    border-radius: 40px;
    padding: 15px;
    box-shadow: var(--shadow-lg);
}

.app-mockup::before {
    content: '';
    position: absolute;
    top: 10px;
    left: 50%;
    transform: translateX(-50%);
    width: 120px;
    height: 25px;
    background: #000;
    border-radius: 0 0 15px 15px;
}

.mockup-screen {
    width: 100%;
    height: 100%;
    background: linear-gradient(135deg, #667eea 0%, #764ba2 100%);
    border-radius: 30px;
    display: flex;
    align-items: center;
    justify-content: center;
    overflow: hidden;
}

.mockup-content {
    text-align: center;
    color: white;
}

.mockup-shapes {
    display: flex;
    gap: 15px;
    justify-content: center;
    margin-bottom: 20px;
}

.shape {
    width: 50px;
    height: 50px;
    animation: bounce 2s ease-in-out infinite;
}

.shape-circle {
    background: #FF6B35;
    border-radius: 50%;
    animation-delay: 0s;
}

.shape-triangle {
    width: 0;
    height: 0;
    border-left: 25px solid transparent;
    border-right: 25px solid transparent;
    border-bottom: 50px solid #4ECDC4;
    background: transparent;
    animation-delay: 0.2s;
}

.shape-square {
    background: #FFE66D;
    animation-delay: 0.4s;
}

.mockup-text {
    font-size: var(--font-lg);
    font-weight: 600;
}

/* 浮动装饰元素 */
.floating-shapes {
    position: absolute;
    top: 0;
    left: 0;
    right: 0;
    bottom: 0;
    pointer-events: none;
    overflow: hidden;
}

.float-shape {
    position: absolute;
    font-size: 3rem;
    opacity: 0.3;
    animation: float 6s ease-in-out infinite;
}

.float-shape-1 {
    top: 20%;
    left: 10%;
    animation-delay: 0s;
}

.float-shape-2 {
    top: 60%;
    right: 10%;
    animation-delay: 1.5s;
}

.float-shape-3 {
    bottom: 20%;
    left: 20%;
    animation-delay: 3s;
}

.float-shape-4 {
    top: 30%;
    right: 25%;
    animation-delay: 4.5s;
}

/* ============================================
   核心功能
   ============================================ */
.features {
    padding: var(--spacing-xxl) 0;
    background: var(--bg-white);
}

.section-title {
    text-align: center;
    font-size: var(--font-4xl);
    font-weight: 800;
    color: var(--text-dark);
    margin-bottom: var(--spacing-sm);
}

.section-subtitle {
    text-align: center;
    font-size: var(--font-lg);
    color: var(--text-light);
    margin-bottom: var(--spacing-xl);
}

.features-grid {
    display: grid;
    grid-template-columns: repeat(3, 1fr);
    gap: var(--spacing-lg);
}

.feature-card {
    background: var(--bg-white);
    border-radius: var(--radius-lg);
    padding: var(--spacing-lg);
    text-align: center;
    box-shadow: var(--shadow-md);
    transition: all 0.3s ease;
    position: relative;
    overflow: hidden;
}

.feature-card::before {
    content: '';
    position: absolute;
    top: 0;
    left: 0;
    right: 0;
    height: 4px;
}

.feature-ai::before {
    background: var(--gradient-primary);
}

.feature-exam::before {
    background: var(--gradient-secondary);
}

.feature-report::before {
    background: linear-gradient(135deg, #FFE66D 0%, #FFD93D 100%);
}

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

.feature-icon {
    width: 80px;
    height: 80px;
    margin: 0 auto var(--spacing-md);
    display: flex;
    align-items: center;
    justify-content: center;
    border-radius: var(--radius-full);
    background: var(--bg-light);
}

.icon-emoji {
    font-size: 2.5rem;
}

.feature-card h3 {
    font-size: var(--font-xl);
    font-weight: 700;
    color: var(--text-dark);
    margin-bottom: var(--spacing-sm);
}

.feature-card p {
    font-size: var(--font-base);
    color: var(--text-light);
    margin-bottom: var(--spacing-md);
}

.feature-list {
    text-align: left;
    margin-bottom: var(--spacing-md);
}

.feature-list li {
    padding: var(--spacing-xs) 0;
    color: var(--text-dark);
    position: relative;
    padding-left: 25px;
}

.feature-list li::before {
    content: '✓';
    position: absolute;
    left: 0;
    color: var(--secondary-color);
    font-weight: 700;
}

.feature-badge {
    display: inline-block;
    padding: var(--spacing-xs) var(--spacing-sm);
    background: var(--bg-light);
    border-radius: var(--radius-sm);
    font-size: var(--font-sm);
    font-weight: 600;
    color: var(--primary-color);
}

/* ============================================
   使用方法
   ============================================ */
.how-it-works {
    padding: var(--spacing-xxl) 0;
    background: linear-gradient(135deg, #FFF5F0 0%, #FFF0E6 100%);
}

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

.step {
    text-align: center;
    padding: var(--spacing-lg);
    background: var(--bg-white);
    border-radius: var(--radius-lg);
    box-shadow: var(--shadow-md);
    min-width: 200px;
    flex: 1;
    max-width: 280px;
    transition: all 0.3s ease;
}

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

.step-number {
    width: 40px;
    height: 40px;
    margin: 0 auto var(--spacing-sm);
    display: flex;
    align-items: center;
    justify-content: center;
    background: var(--gradient-primary);
    color: var(--text-white);
    font-weight: 700;
    font-size: var(--font-lg);
    border-radius: var(--radius-full);
}

.step-icon {
    font-size: 3rem;
    margin-bottom: var(--spacing-sm);
}

.step h3 {
    font-size: var(--font-lg);
    font-weight: 700;
    color: var(--text-dark);
    margin-bottom: var(--spacing-xs);
}

.step p {
    font-size: var(--font-sm);
    color: var(--text-light);
}

.step-connector {
    width: 60px;
    color: var(--primary-color);
}

.connector-arrow {
    width: 100%;
    height: auto;
}

/* ============================================
   适用人群
   ============================================ */
.audience {
    padding: var(--spacing-xxl) 0;
    background: var(--bg-white);
}

.audience-cards {
    display: grid;
    grid-template-columns: repeat(3, 1fr);
    gap: var(--spacing-lg);
}

.audience-card {
    text-align: center;
    padding: var(--spacing-lg);
    background: var(--bg-light);
    border-radius: var(--radius-lg);
    transition: all 0.3s ease;
}

.audience-card:hover {
    background: var(--bg-white);
    box-shadow: var(--shadow-md);
    transform: translateY(-5px);
}

.audience-icon {
    font-size: 3rem;
    margin-bottom: var(--spacing-md);
}

.audience-card h3 {
    font-size: var(--font-lg);
    font-weight: 700;
    color: var(--text-dark);
    margin-bottom: var(--spacing-xs);
}

.audience-card p {
    font-size: var(--font-base);
    color: var(--text-light);
}

/* ============================================
   下载CTA
   ============================================ */
.download-cta {
    padding: var(--spacing-xxl) 0;
    background: var(--gradient-hero);
    color: var(--text-white);
    text-align: center;
}

.cta-content h2 {
    font-size: var(--font-4xl);
    font-weight: 800;
    margin-bottom: var(--spacing-sm);
}

.cta-content p {
    font-size: var(--font-lg);
    opacity: 0.9;
    margin-bottom: var(--spacing-lg);
}

.cta-buttons {
    justify-content: center;
}

.cta-buttons .ios-btn {
    background: var(--text-white);
    color: var(--text-dark);
}

.cta-buttons .ios-btn:hover {
    background: var(--bg-light);
}

.cta-buttons .android-btn {
    background: var(--secondary-color);
}

/* ============================================
   页脚
   ============================================ */
.footer {
    background: var(--text-dark);
    color: var(--text-white);
    padding: var(--spacing-xl) 0 var(--spacing-md);
}

.footer-content {
    display: grid;
    grid-template-columns: 1fr 2fr 1fr;
    gap: var(--spacing-lg);
    margin-bottom: var(--spacing-lg);
    padding-bottom: var(--spacing-lg);
    border-bottom: 1px solid rgba(255, 255, 255, 0.1);
}

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

.footer-logo .logo-icon {
    font-size: 1.5rem;
}

.footer-logo .logo-text {
    font-size: var(--font-lg);
    font-weight: 700;
    color: var(--text-white);
}

.footer-info p {
    color: rgba(255, 255, 255, 0.7);
    font-size: var(--font-sm);
    margin-bottom: var(--spacing-xs);
}

.footer-links {
    display: flex;
    gap: var(--spacing-md);
    justify-content: flex-end;
}

.footer-links a {
    color: rgba(255, 255, 255, 0.7);
    font-size: var(--font-sm);
    transition: color 0.3s ease;
}

.footer-links a:hover {
    color: var(--text-white);
}

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

.footer-bottom p {
    color: rgba(255, 255, 255, 0.5);
    font-size: var(--font-sm);
}

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

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

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

@keyframes float {
    0%, 100% {
        transform: translateY(0) rotate(0deg);
    }
    50% {
        transform: translateY(-20px) rotate(10deg);
    }
}

/* ============================================
   响应式设计
   ============================================ */
@media (max-width: 1024px) {
    .hero-content {
        grid-template-columns: 1fr;
        text-align: center;
    }
    
    .hero-stats {
        justify-content: center;
    }
    
    .download-buttons {
        justify-content: center;
    }
    
    .hero-image {
        order: -1;
    }
    
    .app-mockup {
        width: 240px;
        height: 480px;
    }
    
    .features-grid {
        grid-template-columns: 1fr;
    }
    
    .audience-cards {
        grid-template-columns: 1fr;
    }
    
    .footer-content {
        grid-template-columns: 1fr;
        text-align: center;
    }
    
    .footer-links {
        justify-content: center;
    }
}

@media (max-width: 768px) {
    :root {
        --font-5xl: 2rem;
        --font-4xl: 1.75rem;
        --font-3xl: 1.5rem;
    }
    
    .nav-links {
        display: none;
    }
    
    .hero {
        padding-top: 100px;
        padding-bottom: var(--spacing-xl);
    }
    
    .hero-stats {
        flex-direction: column;
        gap: var(--spacing-sm);
    }
    
    .stat-item {
        width: 100%;
    }
    
    .download-buttons {
        flex-direction: column;
        width: 100%;
    }
    
    .download-btn {
        width: 100%;
        justify-content: center;
    }
    
    .steps-container {
        flex-direction: column;
    }
    
    .step-connector {
        transform: rotate(90deg);
        width: 40px;
    }
    
    .app-mockup {
        width: 200px;
        height: 400px;
    }
    
    .shape {
        width: 35px;
        height: 35px;
    }
    
    .shape-triangle {
        border-left: 17.5px solid transparent;
        border-right: 17.5px solid transparent;
        border-bottom: 35px solid #4ECDC4;
    }
}

@media (max-width: 480px) {
    .container {
        padding: 0 var(--spacing-sm);
    }
    
    .hero-text h1 {
        font-size: 1.75rem;
    }
    
    .feature-card {
        padding: var(--spacing-md);
    }
    
    .step {
        min-width: 100%;
    }
}