/* CSS Variables */
:root {
    /* 颜色 */
    --primary-color: #2196F3;
    --primary-dark: #1976D2;
    --primary-light: #4FC3F7;
    --accent-color: #03A9F4;
    --secondary-color: #00BCD4;
    --text-primary: #212121;
    --text-secondary: #757575;
    --text-light: #FFFFFF;
    --bg-primary: #FFFFFF;
    --bg-secondary: #F5F5F5;
    --bg-accent: #E3F2FD;
    --border-color: #E0E0E0;
    --success-color: #4CAF50;
    --error-color: #F44336;
    --warning-color: #FF9800;
    --info-color: #2196F3;
    
    /* 间距 */
    --spacing-xs: 0.5rem;
    --spacing-sm: 1rem;
    --spacing-md: 1.5rem;
    --spacing-lg: 2rem;
    --spacing-xl: 3rem;
    --spacing-xxl: 4rem;
    --spacing-xxxl: 6rem;
    
    /* 圆角 */
    --border-radius-sm: 4px;
    --border-radius-md: 8px;
    --border-radius-lg: 16px;
    --border-radius-full: 50%;
    
    /* 阴影 */
    --shadow-sm: 0 2px 4px rgba(0, 0, 0, 0.1);
    --shadow-md: 0 4px 8px rgba(0, 0, 0, 0.12);
    --shadow-lg: 0 8px 16px rgba(0, 0, 0, 0.14);
    --shadow-xl: 0 16px 32px rgba(0, 0, 0, 0.16);
    --shadow-inset: inset 0 2px 4px rgba(0, 0, 0, 0.06);
    
    /* 字体 */
    --font-family: 'Segoe UI', 'PingFang SC', 'Microsoft YaHei', sans-serif;
    --font-size-xs: 0.75rem;
    --font-size-sm: 0.875rem;
    --font-size-md: 1rem;
    --font-size-lg: 1.25rem;
    --font-size-xl: 1.5rem;
    --font-size-xxl: 2rem;
    --font-size-xxxl: 3rem;
    --font-size-xxxxl: 4rem;
    
    /* 行高 */
    --line-height-xs: 1.2;
    --line-height-sm: 1.4;
    --line-height-md: 1.6;
    --line-height-lg: 1.8;
    
    /* 过渡 */
    --transition-fast: 0.2s ease;
    --transition-normal: 0.3s ease;
    --transition-slow: 0.5s ease;
    
    /* 断点 */
    --breakpoint-sm: 576px;
    --breakpoint-md: 768px;
    --breakpoint-lg: 992px;
    --breakpoint-xl: 1200px;
    --breakpoint-xxl: 1400px;
}

/* Reset Styles */
* {
    margin: 0;
    padding: 0;
    box-sizing: border-box;
}

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

body {
    font-family: var(--font-family);
    font-size: var(--font-size-md);
    line-height: var(--line-height-md);
    color: var(--text-primary);
    background-color: var(--bg-primary);
    -webkit-font-smoothing: antialiased;
    -moz-osx-font-smoothing: grayscale;
}

/* Base Styles */
a {
    color: var(--primary-color);
    text-decoration: none;
    transition: color var(--transition-fast);
}

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

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

ul, ol {
    list-style: none;
}

h1, h2, h3, h4, h5, h6 {
    font-weight: 700;
    line-height: var(--line-height-xs);
    margin-bottom: var(--spacing-md);
}

h1 {
    font-size: var(--font-size-xxxl);
}

h2 {
    font-size: var(--font-size-xxl);
}

h3 {
    font-size: var(--font-size-xl);
}

h4 {
    font-size: var(--font-size-lg);
}

p {
    margin-bottom: var(--spacing-md);
}

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

/* Buttons */
.btn {
    display: inline-flex;
    align-items: center;
    justify-content: center;
    padding: var(--spacing-sm) var(--spacing-lg);
    font-family: var(--font-family);
    font-size: var(--font-size-md);
    font-weight: 600;
    line-height: var(--line-height-xs);
    border: none;
    border-radius: var(--border-radius-md);
    cursor: pointer;
    transition: all var(--transition-normal);
    text-align: center;
    text-decoration: none;
    white-space: nowrap;
}

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

.btn-primary:hover {
    background-color: var(--primary-dark);
    color: var(--text-light);
    transform: translateY(-2px);
    box-shadow: var(--shadow-lg);
}

.btn-secondary {
    background-color: transparent;
    color: var(--primary-color);
    border: 2px solid var(--primary-color);
}

.btn-secondary:hover {
    background-color: var(--primary-color);
    color: var(--text-light);
    transform: translateY(-2px);
    box-shadow: var(--shadow-lg);
}

.btn-platform {
    background-color: var(--bg-secondary);
    color: var(--text-primary);
    border: 1px solid var(--border-color);
    padding: var(--spacing-xs) var(--spacing-md);
    font-size: var(--font-size-sm);
}

.btn-platform:hover {
    background-color: var(--primary-color);
    color: var(--text-light);
    border-color: var(--primary-color);
    transform: translateY(-1px);
    box-shadow: var(--shadow-md);
}

.btn-download {
    background-color: var(--primary-color);
    color: var(--text-light);
    padding: var(--spacing-md) var(--spacing-xl);
    font-size: var(--font-size-lg);
    border-radius: var(--border-radius-lg);
    margin-bottom: var(--spacing-md);
    min-width: 250px;
}

.btn-download:hover {
    background-color: var(--primary-dark);
    transform: translateY(-2px);
    box-shadow: var(--shadow-xl);
}

/* Header */
.header {
    position: fixed;
    top: 0;
    left: 0;
    width: 100%;
    background-color: rgba(255, 255, 255, 0.95);
    backdrop-filter: blur(10px);
    border-bottom: 1px solid var(--border-color);
    z-index: 1000;
    transition: all var(--transition-normal);
}

.header-content {
    display: flex;
    align-items: center;
    justify-content: space-between;
    padding: var(--spacing-sm) 0;
}

.logo {
    display: flex;
    align-items: center;
}

.logo-link {
    display: flex;
    align-items: center;
    color: var(--text-primary);
}

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

.logo-img {
    width: 40px;
    height: 40px;
    margin-right: var(--spacing-xs);
}

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

/* Navigation */
.nav {
    display: flex;
}

.desktop-nav {
    display: flex;
}

.mobile-nav {
    display: none;
}

.nav-list {
    display: flex;
    align-items: center;
    gap: var(--spacing-md);
}

.nav-link {
    position: relative;
    padding: var(--spacing-xs) 0;
    font-weight: 600;
    color: var(--text-primary);
    transition: color var(--transition-fast);
}

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

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

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

/* Mobile Navigation Button */
.mobile-nav-btn {
    display: none;
    align-items: center;
    justify-content: center;
    width: 48px;
    height: 48px;
    background-color: transparent;
    border: none;
    cursor: pointer;
    padding: var(--spacing-xs);
}

.mobile-nav-btn-line {
    display: block;
    width: 24px;
    height: 3px;
    background-color: var(--text-primary);
    border-radius: var(--border-radius-full);
    transition: all var(--transition-normal);
}

.mobile-nav-btn-line:not(:last-child) {
    margin-bottom: 5px;
}

.mobile-nav-btn.active .mobile-nav-btn-line:nth-child(1) {
    transform: rotate(45deg) translate(6px, 6px);
    background-color: var(--text-light);
}

.mobile-nav-btn.active .mobile-nav-btn-line:nth-child(2) {
    opacity: 0;
}

.mobile-nav-btn.active .mobile-nav-btn-line:nth-child(3) {
    transform: rotate(-45deg) translate(6px, -6px);
    background-color: var(--text-light);
}

/* Mobile Navigation */
.mobile-nav {
    position: fixed;
    top: 0;
    right: -100%;
    width: 100%;
    height: 100vh;
    background-color: rgba(33, 150, 243, 0.98);
    backdrop-filter: blur(10px);
    z-index: 1001;
    transition: right var(--transition-normal);
    box-shadow: var(--shadow-xl);
}

.mobile-nav.active {
    right: 0;
}

.mobile-nav .nav-list {
    flex-direction: column;
    align-items: center;
    justify-content: center;
    height: 100%;
    gap: var(--spacing-lg);
}

.mobile-nav .nav-link {
    font-size: var(--font-size-xl);
    color: var(--text-light);
    padding: var(--spacing-sm) var(--spacing-lg);
    border-radius: var(--border-radius-md);
    transition: all var(--transition-normal);
}

.mobile-nav .nav-link:hover {
    color: var(--text-light);
    background-color: rgba(255, 255, 255, 0.2);
    transform: translateY(-2px);
}

.mobile-nav .nav-link::after {
    background-color: var(--text-light);
}

/* Mobile Navigation Overlay */
.mobile-nav-overlay {
    display: none;
    position: fixed;
    top: 0;
    left: 0;
    width: 100%;
    height: 100vh;
    background-color: rgba(0, 0, 0, 0.5);
    backdrop-filter: blur(2px);
    z-index: 1000;
    transition: opacity var(--transition-normal);
    opacity: 0;
}

.mobile-nav-overlay.active {
    display: block;
    opacity: 1;
}

/* Hero Section */
.hero {
    padding: var(--spacing-xxxl) 0 var(--spacing-xxl);
    background: linear-gradient(135deg, var(--bg-accent) 0%, var(--bg-primary) 100%);
    margin-top: 70px;
}

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

.hero-text h1 {
    margin-bottom: var(--spacing-md);
    background: linear-gradient(135deg, var(--primary-color), var(--secondary-color));
    -webkit-background-clip: text;
    -webkit-text-fill-color: transparent;
    background-clip: text;
}

.hero-desc {
    font-size: var(--font-size-lg);
    color: var(--text-secondary);
    margin-bottom: var(--spacing-xl);
}

.hero-buttons {
    display: flex;
    gap: var(--spacing-md);
    flex-wrap: wrap;
}

.hero-image {
    display: flex;
    align-items: center;
    justify-content: center;
}

.product-showcase {
    position: relative;
    width: 100%;
    max-width: 400px;
    height: 300px;
}

.product-screen {
    position: absolute;
    top: 50%;
    left: 50%;
    transform: translate(-50%, -50%);
    width: 80%;
    height: 80%;
    background-color: var(--bg-primary);
    border-radius: var(--border-radius-lg);
    box-shadow: var(--shadow-xl);
    overflow: hidden;
    animation: float 3s ease-in-out infinite;
}

.screen-content {
    padding: var(--spacing-lg);
    height: 100%;
    display: flex;
    flex-direction: column;
    justify-content: center;
    align-items: center;
    background: linear-gradient(135deg, var(--primary-light), var(--primary-color));
    color: var(--text-light);
}

.screen-title {
    font-size: var(--font-size-xl);
    font-weight: 700;
    margin-bottom: var(--spacing-md);
}

.screen-feature {
    font-size: var(--font-size-md);
    margin-bottom: var(--spacing-sm);
    text-align: center;
}

/* Features Section */
.features {
    padding: var(--spacing-xxl) 0;
    background-color: var(--bg-primary);
}

.section-header {
    text-align: center;
    margin-bottom: var(--spacing-xxl);
}

.section-title {
    margin-bottom: var(--spacing-sm);
    color: var(--primary-color);
}

.section-subtitle {
    font-size: var(--font-size-lg);
    color: var(--text-secondary);
    margin-bottom: 0;
}

.features-grid {
    display: grid;
    grid-template-columns: repeat(4, 1fr);
    gap: var(--spacing-lg);
}

.feature-card {
    background-color: var(--bg-primary);
    border: 1px solid var(--border-color);
    border-radius: var(--border-radius-lg);
    padding: var(--spacing-xl);
    text-align: center;
    transition: all var(--transition-normal);
    box-shadow: var(--shadow-sm);
}

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

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

.feature-card:hover .feature-icon {
    background-color: var(--primary-color);
    color: var(--text-light);
    transform: scale(1.1);
}

.feature-title {
    margin-bottom: var(--spacing-xs);
}

.feature-desc {
    color: var(--text-secondary);
    margin-bottom: 0;
}

/* AI Assistant Section */
.ai-assistant {
    padding: var(--spacing-xxl) 0;
    background: linear-gradient(135deg, var(--primary-color), var(--secondary-color));
    color: var(--text-light);
}

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

.ai-image {
    display: flex;
    align-items: center;
    justify-content: center;
}

.ai-illustration {
    width: 100%;
    max-width: 400px;
    height: 400px;
}

.ai-text .section-title {
    color: var(--text-light);
    margin-bottom: var(--spacing-sm);
}

.ai-text .section-subtitle {
    color: rgba(255, 255, 255, 0.8);
    margin-bottom: var(--spacing-xl);
}

.ai-features {
    display: flex;
    flex-direction: column;
    gap: var(--spacing-md);
}

.ai-feature-item {
    display: flex;
    align-items: center;
    gap: var(--spacing-sm);
    font-size: var(--font-size-lg);
    padding: var(--spacing-sm);
    background-color: rgba(255, 255, 255, 0.1);
    border-radius: var(--border-radius-md);
    transition: all var(--transition-normal);
}

.ai-feature-item:hover {
    background-color: rgba(255, 255, 255, 0.2);
    transform: translateX(5px);
}

.ai-feature-item svg {
    color: var(--success-color);
    flex-shrink: 0;
}

/* Platforms Section */
.platforms {
    padding: var(--spacing-xxl) 0;
    background-color: var(--bg-secondary);
}

.platforms-grid {
    display: grid;
    grid-template-columns: repeat(4, 1fr);
    gap: var(--spacing-lg);
}

.platform-card {
    background-color: var(--bg-primary);
    border: 1px solid var(--border-color);
    border-radius: var(--border-radius-lg);
    padding: var(--spacing-xl);
    text-align: center;
    transition: all var(--transition-normal);
    box-shadow: var(--shadow-sm);
}

.platform-card:hover {
    transform: translateY(-5px);
    box-shadow: var(--shadow-lg);
    border-color: var(--primary-color);
}

.platform-icon {
    width: 100px;
    height: 100px;
    margin: 0 auto var(--spacing-md);
    display: flex;
    align-items: center;
    justify-content: center;
    background-color: var(--bg-accent);
    border-radius: var(--border-radius-full);
    color: var(--primary-color);
    transition: all var(--transition-normal);
}

.platform-card:hover .platform-icon {
    background-color: var(--primary-color);
    color: var(--text-light);
    transform: scale(1.1);
}

.platform-title {
    margin-bottom: var(--spacing-xs);
}

.platform-desc {
    color: var(--text-secondary);
    margin-bottom: var(--spacing-md);
}

/* Download Section */
.download {
    padding: var(--spacing-xxl) 0;
    background-color: var(--bg-primary);
}

.download-content {
    text-align: center;
    max-width: 800px;
    margin: 0 auto;
}

.download-buttons {
    display: flex;
    flex-direction: column;
    align-items: center;
    gap: var(--spacing-md);
    margin-top: var(--spacing-xl);
    margin-bottom: var(--spacing-xl);
}

.download-btn svg {
    margin-right: var(--spacing-xs);
}

.download-note {
    font-size: var(--font-size-sm);
    color: var(--text-secondary);
}

/* Footer */
.footer {
    background-color: var(--text-primary);
    color: var(--text-light);
    padding: var(--spacing-xxl) 0 var(--spacing-lg);
}

.footer-content {
    display: grid;
    grid-template-columns: repeat(4, 1fr);
    gap: var(--spacing-xl);
    margin-bottom: var(--spacing-xl);
}

.footer-column-title {
    margin-bottom: var(--spacing-md);
    color: var(--primary-color);
}

.footer-logo {
    display: flex;
    align-items: center;
    margin-bottom: var(--spacing-md);
}

.footer-logo-img {
    width: 40px;
    height: 40px;
    margin-right: var(--spacing-xs);
}

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

.footer-desc {
    color: rgba(255, 255, 255, 0.7);
    margin-bottom: 0;
}

.footer-links {
    display: flex;
    flex-direction: column;
    gap: var(--spacing-sm);
}

.footer-link {
    color: rgba(255, 255, 255, 0.7);
    transition: all var(--transition-fast);
}

.footer-link:hover {
    color: var(--text-light);
    transform: translateX(5px);
}

.footer-bottom {
    padding-top: var(--spacing-lg);
    border-top: 1px solid rgba(255, 255, 255, 0.1);
    text-align: center;
    color: rgba(255, 255, 255, 0.5);
}

/* Back to Top Button */
.back-to-top {
    position: fixed;
    bottom: var(--spacing-lg);
    right: var(--spacing-lg);
    width: 50px;
    height: 50px;
    background-color: var(--primary-color);
    color: var(--text-light);
    border: none;
    border-radius: var(--border-radius-full);
    cursor: pointer;
    display: flex;
    align-items: center;
    justify-content: center;
    box-shadow: var(--shadow-lg);
    transition: all var(--transition-normal);
    opacity: 0;
    visibility: hidden;
    z-index: 999;
}

.back-to-top:hover {
    background-color: var(--primary-dark);
    transform: translateY(-5px);
    box-shadow: var(--shadow-xl);
}

.back-to-top.active {
    opacity: 1;
    visibility: visible;
}

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

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

/* Utility Classes */
.no-scroll {
    overflow: hidden;
}

/* Responsive Design */
@media (max-width: 1200px) {
    .container {
        max-width: 960px;
    }
    
    .hero-content,
    .ai-content {
        gap: var(--spacing-xl);
    }
    
    .features-grid,
    .platforms-grid,
    .footer-content {
        grid-template-columns: repeat(2, 1fr);
    }
}

@media (max-width: 992px) {
    .container {
        max-width: 720px;
    }
    
    .hero-content,
    .ai-content {
        grid-template-columns: 1fr;
        text-align: center;
    }
    
    .hero-image,
    .ai-image {
        order: -1;
    }
    
    .hero-buttons {
        justify-content: center;
    }
}

@media (max-width: 768px) {
    .container {
        max-width: 540px;
    }
    
    .desktop-nav {
        display: none;
    }
    
    .mobile-nav-btn {
        display: flex;
    }
    
    .mobile-nav {
        display: block;
    }
    
    h1 {
        font-size: var(--font-size-xxl);
    }
    
    h2 {
        font-size: var(--font-size-xl);
    }
    
    .hero {
        padding: var(--spacing-xxl) 0 var(--spacing-xl);
    }
    
    .hero-content {
        gap: var(--spacing-lg);
    }
    
    .hero-buttons {
        flex-direction: column;
        align-items: center;
    }
    
    .features-grid,
    .platforms-grid,
    .footer-content {
        grid-template-columns: 1fr;
    }
    
    .ai-feature-item {
        font-size: var(--font-size-md);
    }
    
    .download-buttons {
        width: 100%;
    }
    
    .btn-download {
        width: 100%;
        min-width: auto;
    }
}

@media (max-width: 576px) {
    .container {
        padding: 0 var(--spacing-sm);
    }
    
    h1 {
        font-size: var(--font-size-xl);
    }
    
    h2 {
        font-size: var(--font-size-lg);
    }
    
    .hero {
        padding: var(--spacing-xl) 0 var(--spacing-lg);
    }
    
    .hero-desc {
        font-size: var(--font-size-md);
    }
    
    .hero-buttons {
        gap: var(--spacing-sm);
    }
    
    .btn {
        padding: var(--spacing-sm) var(--spacing-md);
        font-size: var(--font-size-sm);
    }
    
    .feature-card,
    .platform-card {
        padding: var(--spacing-lg);
    }
    
    .ai-feature-item {
        font-size: var(--font-size-sm);
        padding: var(--spacing-xs);
    }
    
    .footer-content {
        gap: var(--spacing-lg);
    }
}