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

:root {
    /* Color Palette - Dark Theme */
    --primary-color: #8b5cf6;
    --primary-dark: #7c3aed;
    --primary-light: #a78bfa;
    --secondary-color: #10b981;
    --accent-color: #f59e0b;
    --dark-color: #000000;
    --gray-900: #f9fafb;
    --gray-800: #f3f4f6;
    --gray-700: #e5e7eb;
    --gray-600: #d1d5db;
    --gray-500: #9ca3af;
    --gray-400: #6b7280;
    --gray-300: #4b5563;
    --gray-200: #374151;
    --gray-100: #1f2937;
    --white: #ffffff;
    
    /* Piano Colors */
    --piano-white: #ffffff;
    --piano-black: #2d3748;
    --note-green: #10b981;
    --note-blue: #3b82f6;
    --note-purple: #8b5cf6;
    --note-orange: #f59e0b;
    
    /* Typography */
    --font-primary: 'Inter', -apple-system, BlinkMacSystemFont, 'Segoe UI', Roboto, sans-serif;
    --font-mono: 'JetBrains Mono', 'Fira Code', Consolas, 'Courier New', monospace;
    
    /* Spacing */
    --spacing-xs: 0.25rem;
    --spacing-sm: 0.5rem;
    --spacing-md: 1rem;
    --spacing-lg: 1.5rem;
    --spacing-xl: 2rem;
    --spacing-2xl: 3rem;
    --spacing-3xl: 4rem;
    
    /* Shadows */
    --shadow-sm: 0 1px 2px 0 rgba(0, 0, 0, 0.05);
    --shadow-md: 0 4px 6px -1px rgba(0, 0, 0, 0.1), 0 2px 4px -1px rgba(0, 0, 0, 0.06);
    --shadow-lg: 0 10px 15px -3px rgba(0, 0, 0, 0.1), 0 4px 6px -2px rgba(0, 0, 0, 0.05);
    --shadow-xl: 0 20px 25px -5px rgba(0, 0, 0, 0.1), 0 10px 10px -5px rgba(0, 0, 0, 0.04);
    
    /* Transitions */
    --transition-fast: 0.15s ease-in-out;
    --transition-normal: 0.3s ease-in-out;
    --transition-slow: 0.5s ease-in-out;
    
    /* Border Radius */
    --radius-sm: 0.375rem;
    --radius-md: 0.5rem;
    --radius-lg: 0.75rem;
    --radius-xl: 1rem;
    --radius-2xl: 1.5rem;
}

html {
    scroll-behavior: smooth;
}

body {
    font-family: var(--font-primary);
    line-height: 1.6;
    color: var(--gray-900);
    background-color: var(--white);
    overflow-x: hidden;
}

.container {
    max-width: 1200px;
    margin: 0 auto;
    padding: 0 var(--spacing-lg);
}

/* Typography */
h1, h2, h3, h4, h5, h6 {
    font-weight: 600;
    line-height: 1.3;
    margin-bottom: var(--spacing-md);
}

h1 { font-size: 3rem; }
h2 { font-size: 2.5rem; }
h3 { font-size: 2rem; }
h4 { font-size: 1.5rem; }
h5 { font-size: 1.25rem; }
h6 { font-size: 1.125rem; }

p {
    margin-bottom: var(--spacing-md);
    color: var(--gray-600);
}

/* Buttons */
.btn {
    display: inline-flex;
    align-items: center;
    gap: var(--spacing-sm);
    padding: var(--spacing-md) var(--spacing-xl);
    font-size: 1rem;
    font-weight: 500;
    text-decoration: none;
    border: none;
    border-radius: var(--radius-lg);
    cursor: pointer;
    transition: all var(--transition-normal);
    position: relative;
    overflow: hidden;
}

.btn-primary {
    background: linear-gradient(135deg, var(--primary-color), var(--primary-dark));
    color: var(--white);
    box-shadow: var(--shadow-md);
}

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

.btn-secondary {
    background: transparent;
    color: var(--gray-900);
    border: 2px solid var(--primary-color);
}

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

/* Navigation */
.navbar {
    position: fixed;
    top: 0;
    left: 0;
    right: 0;
    background: #000000;
    z-index: 1000;
    transition: all var(--transition-normal);
}

.navbar.scrolled {
    background: #000000;
}

.nav-container {
    display: flex;
    align-items: center;
    justify-content: space-between;
    padding: var(--spacing-md) var(--spacing-lg);
}

.nav-logo {
    display: flex;
    align-items: center;
    gap: var(--spacing-sm);
    font-size: 1.5rem;
    font-weight: 700;
    margin-top: 6px;
}

.nav-logo span {
    /* 备用颜色 */
    color: #8b5cf6;
    
    /* 渐变效果 */
    background: linear-gradient(
        90deg,
        #8b5cf6 0%,
        #a78bfa 20%,
        #c084fc 40%,
        #ddd6fe 60%,
        #c084fc 80%,
        #8b5cf6 100%
    );
    background-size: 400% 100%;
    -webkit-background-clip: text;
    -webkit-text-fill-color: transparent;
    background-clip: text;
    animation: nav-gradient-flow 3s linear infinite;
    filter: drop-shadow(0 0 5px rgba(139, 92, 246, 0.4));
    display: inline-block;
    position: relative;
    
    /* Firefox 兼容性 */
    -moz-background-clip: text;
    -moz-text-fill-color: transparent;
}

.nav-logo .logo-image {
    width: 40px;
    height: 40px;
    object-fit: contain;
}

.nav-logo i {
    font-size: 1.75rem;
}

.nav-menu {
    display: flex;
    list-style: none;
    gap: var(--spacing-xl);
}

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

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

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

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

.hamburger {
    display: none;
    flex-direction: column;
    gap: 4px;
    cursor: pointer;
}

.bar {
    width: 25px;
    height: 3px;
    background: var(--white);
    transition: all var(--transition-normal);
}

/* Hero Section */
.hero {
    min-height: 100vh;
    display: flex;
    align-items: center;
    position: relative;
    background: linear-gradient(135deg, #000000 0%, #1a1a1a 100%);
    overflow: hidden;
    padding-top: 80px;
}

.hero-background {
    position: absolute;
    top: 0;
    left: 0;
    right: 0;
    bottom: 0;
    opacity: 0.1;
}

.piano-keys {
    position: absolute;
    bottom: 0;
    left: 0;
    right: 0;
    height: 100px;
    background: repeating-linear-gradient(
        90deg,
        var(--piano-white) 0,
        var(--piano-white) 30px,
        var(--piano-black) 30px,
        var(--piano-black) 50px
    );
}

.falling-notes {
    position: absolute;
    top: 0;
    left: 0;
    right: 0;
    bottom: 0;
}

.hero .container {
    position: relative;
    z-index: 1;
    height: 100%;
    display: flex;
    align-items: center;
}

.hero-layout {
    display: grid;
    grid-template-columns: 1fr 1fr;
    gap: var(--spacing-3xl);
    align-items: center;
    width: 100%;
    min-height: 70vh;
}

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

.hero-main-image {
    width: 100%;
    max-width: 500px;
    height: auto;
    border-radius: var(--radius-2xl);
    box-shadow: var(--shadow-xl);
    filter: drop-shadow(0 10px 30px rgba(139, 92, 246, 0.3));
    transition: transform var(--transition-normal);
}

.hero-main-image:hover {
    transform: scale(1.02);
}

.hero-content {
    color: var(--white);
    text-align: left;
}

.hero-title {
    font-size: 3.5rem;
    font-weight: 700;
    margin-bottom: var(--spacing-xl);
    line-height: 1.2;
}

.highlight {
    /* 备用颜色 */
    color: #8b5cf6;
    
    /* 渐变效果 */
    background: linear-gradient(
        90deg,
        #8b5cf6 0%,
        #a78bfa 25%,
        #c084fc 50%,
        #ddd6fe 75%,
        #8b5cf6 100%
    );
    background-size: 300% 100%;
    -webkit-background-clip: text;
    -webkit-text-fill-color: transparent;
    background-clip: text;
    animation: hero-gradient-flow 3s linear infinite;
    position: relative;
    display: inline-block;
    filter: drop-shadow(0 0 8px rgba(139, 92, 246, 0.5));
    
    /* Firefox 兼容性 */
    -moz-background-clip: text;
    -moz-text-fill-color: transparent;
}



@keyframes hero-gradient-flow {
    0% {
        background-position: 0% 50%;
    }
    100% {
        background-position: 300% 50%;
    }
}

@keyframes nav-gradient-flow {
    0% {
        background-position: 0% 50%;
    }
    100% {
        background-position: 400% 50%;
    }
}

.hero-subtitle {
    font-size: 1.25rem;
    margin-bottom: var(--spacing-2xl);
    color: rgba(255, 255, 255, 0.9);
    line-height: 1.8;
    text-align: left;
}

.hero-buttons {
    display: flex;
    justify-content: flex-start;
    gap: var(--spacing-lg);
    margin-bottom: var(--spacing-3xl);
}

.hero-stats {
    display: flex;
    justify-content: flex-start;
    gap: var(--spacing-2xl);
}

.stat {
    text-align: center;
}

.stat-number {
    font-size: 2rem;
    font-weight: 700;
    color: var(--white);
}

.stat-label {
    font-size: 0.875rem;
    color: rgba(255, 255, 255, 0.8);
}

/* Phone Mockup */
.hero-image {
    display: flex;
    justify-content: center;
    align-items: center;
}

.phone-mockup {
    width: 300px;
    height: 600px;
    background: linear-gradient(145deg, #e2e8f0, #f1f5f9);
    border-radius: 40px;
    padding: 20px;
    box-shadow: var(--shadow-xl);
    position: relative;
    transform: perspective(1000px) rotateY(-15deg) rotateX(5deg);
}

.phone-screen {
    width: 100%;
    height: 100%;
    background: var(--gray-900);
    border-radius: 30px;
    overflow: hidden;
    position: relative;
}

.waterfall-demo {
    height: 100%;
    background: linear-gradient(180deg, #1a202c 0%, #2d3748 100%);
    position: relative;
}

.demo-piano-keys {
    position: absolute;
    bottom: 0;
    left: 0;
    right: 0;
    height: 80px;
    display: flex;
}

.key {
    flex: 1;
    background: var(--piano-white);
    border: 1px solid var(--gray-300);
    margin: 2px;
    border-radius: 0 0 8px 8px;
}

.key.black {
    background: var(--piano-black);
    height: 50px;
    position: absolute;
    width: 25px;
    z-index: 2;
}

.demo-notes {
    position: absolute;
    top: 0;
    left: 0;
    right: 0;
    bottom: 80px;
}

.note {
    position: absolute;
    width: 25px;
    height: 60px;
    border-radius: var(--radius-sm);
    animation: fall 3s infinite linear;
}

.note-1 { background: var(--note-green); left: 20px; animation-delay: 0s; }
.note-2 { background: var(--note-blue); left: 60px; animation-delay: 0.5s; }
.note-3 { background: var(--note-purple); left: 100px; animation-delay: 1s; }
.note-4 { background: var(--note-orange); left: 140px; animation-delay: 1.5s; }
.note-5 { background: var(--note-green); left: 180px; animation-delay: 2s; }

@keyframes fall {
    from {
        top: -60px;
        opacity: 1;
    }
    to {
        top: 100%;
        opacity: 0;
    }
}

/* Section Styles */
section {
    padding: var(--spacing-3xl) 0;
}

.section-header {
    text-align: center;
    margin-bottom: var(--spacing-3xl);
}

.section-title {
    color: var(--gray-900);
    margin-bottom: var(--spacing-md);
}

.section-subtitle {
    font-size: 1.125rem;
    color: var(--gray-600);
    max-width: 600px;
    margin: 0 auto;
}

/* Features Section */
.features {
    background: linear-gradient(135deg, #000000 0%, #1a1a1a 50%, #000000 100%);
}

.features .section-title {
    color: var(--white);
}

.features .section-subtitle {
    color: rgba(255, 255, 255, 0.9);
}

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

.feature-card {
    background: rgba(255, 255, 255, 0.05);
    padding: var(--spacing-2xl);
    border-radius: var(--radius-xl);
    box-shadow: 0 4px 20px rgba(0, 0, 0, 0.3);
    transition: all var(--transition-normal);
    border: 1px solid rgba(139, 92, 246, 0.2);
    backdrop-filter: blur(10px);
}

.feature-card:hover {
    transform: translateY(-8px);
    box-shadow: 0 8px 40px rgba(139, 92, 246, 0.3);
    border-color: var(--primary-color);
    background: rgba(255, 255, 255, 0.08);
}

.feature-icon {
    width: 60px;
    height: 60px;
    background: linear-gradient(135deg, var(--primary-color), var(--primary-light));
    border-radius: var(--radius-lg);
    display: flex;
    align-items: center;
    justify-content: center;
    margin-bottom: var(--spacing-lg);
}

.feature-icon i {
    font-size: 1.5rem;
    color: var(--white);
}

.feature-title {
    color: var(--white);
    margin-bottom: var(--spacing-md);
}

.feature-description {
    margin-bottom: var(--spacing-lg);
    line-height: 1.7;
    color: rgba(255, 255, 255, 0.9);
}

.feature-list {
    list-style: none;
    padding: 0;
}

.feature-list li {
    position: relative;
    padding-left: var(--spacing-lg);
    margin-bottom: var(--spacing-sm);
    color: rgba(255, 255, 255, 0.8);
}

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



/* Screenshots Section */
.screenshots {
    background: linear-gradient(135deg, #1a1a1a 0%, #000000 50%, #1a1a1a 100%);
}

.screenshots .section-title {
    color: var(--white);
}

.screenshots .section-subtitle {
    color: rgba(255, 255, 255, 0.9);
}

.screenshots-carousel {
    max-width: 1000px;
    margin: 0 auto;
    position: relative;
}

.carousel-container {
    position: relative;
    overflow: hidden;
    border-radius: var(--radius-2xl);
    box-shadow: 0 8px 40px rgba(0, 0, 0, 0.3);
}

.carousel-track {
    position: relative;
    width: 100%;
    height: 400px;
}

.screenshot-slide {
    position: absolute;
    top: 0;
    left: 0;
    width: 100%;
    height: 400px;
    opacity: 0;
    transition: opacity 3s ease-in-out;
    z-index: 1;
    display: flex;
    align-items: center;
    justify-content: center;
}

.screenshot-slide.active {
    opacity: 1;
    z-index: 2;
}

.screenshot-image {
    max-width: 100%;
    max-height: 100%;
    width: auto;
    height: auto;
    object-fit: contain;
    border-radius: var(--radius-lg);
    box-shadow: 0 4px 20px rgba(0, 0, 0, 0.2);
}

/* Navigation buttons */
.carousel-btn {
    position: absolute;
    top: 50%;
    transform: translateY(-50%);
    background: rgba(0, 0, 0, 0.7);
    color: white;
    border: none;
    width: 50px;
    height: 50px;
    border-radius: 50%;
    cursor: pointer;
    font-size: 1.2rem;
    display: flex;
    align-items: center;
    justify-content: center;
    transition: all var(--transition-normal);
    z-index: 10;
    backdrop-filter: blur(10px);
}

.carousel-btn:hover {
    background: rgba(139, 92, 246, 0.8);
    transform: translateY(-50%) scale(1.1);
}

.carousel-btn.prev {
    left: 20px;
}

.carousel-btn.next {
    right: 20px;
}

.carousel-indicators {
    display: flex;
    justify-content: center;
    gap: var(--spacing-sm);
    margin-top: var(--spacing-xl);
}

.indicator {
    width: 12px;
    height: 12px;
    border-radius: 50%;
    background: rgba(255, 255, 255, 0.3);
    cursor: pointer;
    transition: all var(--transition-normal);
    border: 2px solid transparent;
}

.indicator:hover {
    background: rgba(255, 255, 255, 0.5);
    transform: scale(1.1);
}

.indicator.active {
    background: var(--primary-color);
    border-color: rgba(255, 255, 255, 0.3);
    transform: scale(1.2);
}

/* Download Section */
.download {
    background: linear-gradient(135deg, #000000 0%, #1a1a1a 50%, #000000 100%);
    color: var(--white);
}

.download-content {
    display: flex;
    justify-content: center;
    align-items: center;
    text-align: center;
}

.download-info {
    max-width: 600px;
}

.download-title {
    color: var(--white);
    font-size: 2.5rem;
    margin-bottom: var(--spacing-md);
}

.download-subtitle {
    color: rgba(255, 255, 255, 0.9);
    font-size: 1.125rem;
    margin-bottom: var(--spacing-2xl);
}

.download-features {
    margin-bottom: var(--spacing-2xl);
}

.feature-item {
    display: flex;
    align-items: center;
    gap: var(--spacing-md);
    margin-bottom: var(--spacing-md);
}

.feature-item i {
    color: var(--secondary-color);
    font-size: 1.125rem;
}

.download-buttons {
    display: flex;
    gap: var(--spacing-lg);
    margin-bottom: var(--spacing-2xl);
}

.download-btn {
    display: flex;
    align-items: center;
    gap: var(--spacing-md);
    padding: var(--spacing-lg) var(--spacing-xl);
    background: rgba(255, 255, 255, 0.1);
    color: var(--white);
    text-decoration: none;
    border-radius: var(--radius-lg);
    border: 1px solid rgba(255, 255, 255, 0.2);
    transition: all var(--transition-normal);
    backdrop-filter: blur(10px);
}

.download-btn:hover {
    background: rgba(255, 255, 255, 0.15);
    transform: translateY(-2px);
    box-shadow: var(--shadow-lg);
}

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

.download-btn.primary:hover {
    background: var(--gray-100);
}

.download-btn i {
    font-size: 1.5rem;
}

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

.btn-label {
    font-size: 0.75rem;
    opacity: 0.8;
}

.btn-store {
    font-size: 1rem;
    font-weight: 600;
}

.system-requirements {
    background: rgba(255, 255, 255, 0.1);
    padding: var(--spacing-lg);
    border-radius: var(--radius-lg);
    backdrop-filter: blur(10px);
}

.system-requirements h4 {
    color: var(--white);
    margin-bottom: var(--spacing-md);
}

.system-requirements ul {
    list-style: none;
    padding: 0;
}

.system-requirements li {
    color: rgba(255, 255, 255, 0.9);
    margin-bottom: var(--spacing-sm);
    position: relative;
    padding-left: var(--spacing-lg);
}

.system-requirements li::before {
    content: '•';
    position: absolute;
    left: 0;
    color: var(--secondary-color);
}

/* App Showcase */
.app-showcase {
    display: flex;
    justify-content: center;
}

.phone-frame {
    width: 280px;
    height: 560px;
    background: linear-gradient(145deg, #2d3748, #4a5568);
    border-radius: 35px;
    padding: 15px;
    box-shadow: var(--shadow-xl);
    transform: perspective(1000px) rotateY(15deg) rotateX(-5deg);
}

.screen {
    width: 100%;
    height: 100%;
    background: var(--gray-900);
    border-radius: 25px;
    overflow: hidden;
    position: relative;
}

.status-bar {
    display: flex;
    justify-content: space-between;
    align-items: center;
    padding: var(--spacing-sm) var(--spacing-md);
    background: rgba(0, 0, 0, 0.3);
    color: var(--white);
    font-size: 0.875rem;
}

.indicators {
    display: flex;
    gap: var(--spacing-xs);
}

.app-content {
    padding: var(--spacing-lg);
    height: calc(100% - 30px);
}

.app-header {
    display: flex;
    justify-content: space-between;
    align-items: center;
    margin-bottom: var(--spacing-lg);
}

.app-header h3 {
    color: var(--white);
    margin: 0;
}

.play-btn {
    width: 40px;
    height: 40px;
    border-radius: 50%;
    background: var(--primary-color);
    border: none;
    color: var(--white);
    cursor: pointer;
    display: flex;
    align-items: center;
    justify-content: center;
}

.app-waterfall {
    height: 60%;
    background: linear-gradient(180deg, transparent, rgba(0, 0, 0, 0.3));
    margin-bottom: var(--spacing-lg);
    position: relative;
    border-radius: var(--radius-md);
}

.note-lane {
    position: absolute;
    width: 20px;
    height: 40px;
    background: var(--primary-color);
    border-radius: var(--radius-sm);
    animation: fall-demo 2s infinite linear;
}

.note-lane:nth-child(1) { left: 20px; animation-delay: 0s; }
.note-lane:nth-child(2) { left: 60px; animation-delay: 0.5s; }
.note-lane:nth-child(3) { left: 100px; animation-delay: 1s; }
.note-lane:nth-child(4) { left: 140px; animation-delay: 1.5s; }

@keyframes fall-demo {
    from { top: -40px; opacity: 1; }
    to { top: 100%; opacity: 0; }
}

.app-keyboard {
    display: flex;
    height: 60px;
    gap: 2px;
}

.app-keyboard .key {
    flex: 1;
    background: var(--white);
    border-radius: 0 0 var(--radius-sm) var(--radius-sm);
}

.app-keyboard .key.black {
    background: var(--piano-black);
    height: 40px;
    position: absolute;
    width: 15px;
    z-index: 2;
}

/* Horizontal Phone Frame */
.phone-frame-horizontal {
    width: 500px;
    height: 300px;
    background: linear-gradient(145deg, #2d3748, #4a5568);
    border-radius: 15px;
    padding: 8px;
    box-shadow: var(--shadow-xl);
    transform: none;
}

.screen-horizontal {
    width: 100%;
    height: 100%;
    background: var(--gray-900);
    border-radius: 10px;
    overflow: hidden;
    position: relative;
    display: flex;
    align-items: center;
    justify-content: center;
}

.piano-interface-img {
    width: 100%;
    height: 100%;
    object-fit: cover;
    border-radius: 10px;
}

/* Contact Section */
.contact {
    background: linear-gradient(135deg, #fefefe 0%, #f8f9fa 50%, #ffffff 100%);
}

.contact .section-title {
    color: #1f2937;
}

.contact .section-subtitle {
    color: #4b5563;
}

.contact-content {
    display: grid;
    grid-template-columns: 1fr 1fr;
    gap: var(--spacing-3xl);
}

.contact-info {
    display: flex;
    flex-direction: column;
    gap: var(--spacing-xl);
}

.contact-item {
    display: flex;
    gap: var(--spacing-lg);
    padding: var(--spacing-xl);
    background: rgba(255, 255, 255, 0.9);
    border-radius: var(--radius-lg);
    box-shadow: 0 2px 15px rgba(0, 0, 0, 0.05);
    border: 1px solid rgba(139, 92, 246, 0.1);
    transition: all var(--transition-normal);
}

.contact-item:hover {
    transform: translateY(-4px);
    box-shadow: 0 8px 25px rgba(139, 92, 246, 0.15);
    border-color: rgba(139, 92, 246, 0.2);
}

.contact-icon {
    width: 60px;
    height: 60px;
    background: linear-gradient(135deg, var(--primary-color), var(--primary-light));
    border-radius: var(--radius-lg);
    display: flex;
    align-items: center;
    justify-content: center;
    flex-shrink: 0;
}

.contact-icon i {
    font-size: 1.5rem;
    color: var(--white);
}

.contact-details h4 {
    color: #1f2937;
    margin-bottom: var(--spacing-sm);
}

.contact-details p {
    color: #4b5563;
    margin: 0;
}

.contact-form {
    background: rgba(255, 255, 255, 0.9);
    padding: var(--spacing-2xl);
    border-radius: var(--radius-xl);
    box-shadow: 0 4px 20px rgba(0, 0, 0, 0.05);
    border: 1px solid rgba(139, 92, 246, 0.1);
}

.form {
    display: flex;
    flex-direction: column;
    gap: var(--spacing-lg);
}

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

.form-group label {
    font-weight: 500;
    color: #374151;
}

.form-group input,
.form-group select,
.form-group textarea {
    padding: var(--spacing-md);
    border: 2px solid #e5e7eb;
    border-radius: var(--radius-md);
    font-size: 1rem;
    background: rgba(255, 255, 255, 0.7);
    transition: all var(--transition-fast);
}

.form-group input:focus,
.form-group select:focus,
.form-group textarea:focus {
    outline: none;
    border-color: var(--primary-color);
    background: rgba(255, 255, 255, 1);
    box-shadow: 0 0 0 3px rgba(139, 92, 246, 0.1);
}

.form-group textarea {
    resize: vertical;
    min-height: 120px;
}

/* Footer */
.footer {
    background: var(--gray-900);
    color: var(--white);
    padding: var(--spacing-3xl) 0 var(--spacing-xl);
}

.footer-content {
    display: grid;
    grid-template-columns: 2fr 1fr 1fr 1fr;
    gap: var(--spacing-2xl);
    margin-bottom: var(--spacing-2xl);
}

.footer-logo {
    display: flex;
    align-items: center;
    gap: var(--spacing-sm);
    font-size: 1.5rem;
    font-weight: 700;
    margin-bottom: var(--spacing-lg);
}

.footer-logo .footer-logo-image {
    width: 30px;
    height: 30px;
    object-fit: contain;
}

.footer-description {
    color: var(--gray-400);
    margin-bottom: var(--spacing-xl);
    line-height: 1.7;
}

.social-links {
    display: flex;
    gap: var(--spacing-md);
}

.social-link {
    width: 40px;
    height: 40px;
    background: rgba(255, 255, 255, 0.1);
    border-radius: var(--radius-md);
    display: flex;
    align-items: center;
    justify-content: center;
    color: var(--white);
    text-decoration: none;
    transition: all var(--transition-normal);
}

.social-link:hover {
    background: var(--primary-color);
    transform: translateY(-2px);
}

.footer-title {
    color: var(--white);
    margin-bottom: var(--spacing-lg);
    font-size: 1.125rem;
}

.footer-links {
    list-style: none;
    padding: 0;
}

.footer-links li {
    margin-bottom: var(--spacing-sm);
}

.footer-links a {
    color: var(--gray-400);
    text-decoration: none;
    transition: color var(--transition-fast);
}

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

.footer-bottom {
    display: flex;
    justify-content: space-between;
    align-items: center;
    padding-top: var(--spacing-xl);
    border-top: 1px solid var(--gray-700);
}

.footer-copyright p,
.footer-version p {
    color: var(--gray-400);
    margin: 0;
    font-size: 0.875rem;
}

/* Back to Top Button */
.back-to-top {
    position: fixed;
    bottom: 30px;
    right: 30px;
    width: 50px;
    height: 50px;
    background: var(--primary-color);
    color: var(--white);
    border: none;
    border-radius: 50%;
    cursor: pointer;
    display: none;
    align-items: center;
    justify-content: center;
    box-shadow: var(--shadow-lg);
    transition: all var(--transition-normal);
    z-index: 1000;
}

.back-to-top:hover {
    background: var(--primary-dark);
    transform: translateY(-3px);
}

.back-to-top.show {
    display: flex;
}

/* Responsive Design */
@media (max-width: 1024px) {
    .container {
        padding: 0 var(--spacing-md);
    }
    
    .hero-layout {
        gap: var(--spacing-2xl);
    }
    
    .hero-main-image {
        max-width: 400px;
    }
    
    .download-content {
        text-align: center;
    }
    
    .contact-content {
        grid-template-columns: 1fr;
    }
    
    .footer-content {
        grid-template-columns: 1fr 1fr;
        gap: var(--spacing-xl);
    }
}

@media (max-width: 768px) {
    .nav-menu {
        position: fixed;
        top: 100%;
        left: 0;
        right: 0;
        background: #000000;
        flex-direction: column;
        padding: var(--spacing-xl);
        transform: translateY(-100%);
        transition: transform var(--transition-normal);
        opacity: 0;
        visibility: hidden;
    }
    
    .nav-menu.active {
        transform: translateY(0);
        opacity: 1;
        visibility: visible;
    }
    
    .hamburger {
        display: flex;
    }
    
    .hamburger.active .bar:nth-child(1) {
        transform: rotate(45deg) translate(5px, 5px);
    }
    
    .hamburger.active .bar:nth-child(2) {
        opacity: 0;
    }
    
    .hamburger.active .bar:nth-child(3) {
        transform: rotate(-45deg) translate(7px, -6px);
    }
    
    .hero-layout {
        grid-template-columns: 1fr;
        gap: var(--spacing-2xl);
        text-align: center;
    }
    
    .hero-image-section {
        order: -1;
    }
    
    .hero-content {
        text-align: center;
    }
    
    .hero-subtitle {
        text-align: center;
    }
    
    .hero-title {
        font-size: 2.5rem;
    }
    
    .hero-buttons {
        justify-content: center;
        flex-direction: column;
        align-items: center;
    }
    
    .hero-stats {
        justify-content: center;
    }
    
    .features-grid {
        grid-template-columns: 1fr;
    }
    
    .screenshots-carousel {
        max-width: 100%;
    }
    
    .screenshot-slide {
        height: 300px;
    }
    
    .carousel-btn {
        width: 40px;
        height: 40px;
        font-size: 1rem;
    }
    
    .carousel-btn.prev {
        left: 10px;
    }
    
    .carousel-btn.next {
        right: 10px;
    }
    
    .download-buttons {
        flex-direction: column;
    }
    
    .footer-content {
        grid-template-columns: 1fr;
        text-align: center;
    }
    
    .footer-bottom {
        flex-direction: column;
        gap: var(--spacing-md);
        text-align: center;
    }
    
    .phone-mockup,
    .phone-frame,
    .phone-frame-horizontal {
        transform: none;
        width: 100%;
        max-width: 300px;
    }
    
    .phone-frame-horizontal {
        height: 200px;
        max-width: 400px;
    }
}

@media (max-width: 480px) {
    h1 { font-size: 2rem; }
    h2 { font-size: 1.75rem; }
    h3 { font-size: 1.5rem; }
    
    .hero-title {
        font-size: 2rem;
    }
    
    .hero-subtitle {
        font-size: 1rem;
    }
    
    .container {
        padding: 0 var(--spacing-sm);
    }
    
    section {
        padding: var(--spacing-2xl) 0;
    }
    
    .btn {
        padding: var(--spacing-sm) var(--spacing-lg);
        font-size: 0.875rem;
    }
}

/* Utility Classes */
.text-center { text-align: center; }
.text-left { text-align: left; }
.text-right { text-align: right; }

.mt-0 { margin-top: 0; }
.mt-1 { margin-top: var(--spacing-xs); }
.mt-2 { margin-top: var(--spacing-sm); }
.mt-3 { margin-top: var(--spacing-md); }
.mt-4 { margin-top: var(--spacing-lg); }
.mt-5 { margin-top: var(--spacing-xl); }

.mb-0 { margin-bottom: 0; }
.mb-1 { margin-bottom: var(--spacing-xs); }
.mb-2 { margin-bottom: var(--spacing-sm); }
.mb-3 { margin-bottom: var(--spacing-md); }
.mb-4 { margin-bottom: var(--spacing-lg); }
.mb-5 { margin-bottom: var(--spacing-xl); }

.d-none { display: none; }
.d-block { display: block; }
.d-flex { display: flex; }
.d-grid { display: grid; }

.fade-in {
    opacity: 0;
    transform: translateY(20px);
    transition: all 0.6s ease-out;
}

.fade-in.visible {
    opacity: 1;
    transform: translateY(0);
}

/* Loading States */
.loading {
    position: relative;
    pointer-events: none;
}

.loading::after {
    content: '';
    position: absolute;
    top: 50%;
    left: 50%;
    width: 20px;
    height: 20px;
    margin: -10px 0 0 -10px;
    border: 2px solid var(--gray-300);
    border-top-color: var(--primary-color);
    border-radius: 50%;
    animation: spin 1s linear infinite;
}

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

/* 字体动画效果 */
.hero h1 {
    animation: fadeInUp 1.5s ease-out;
}

.hero p {
    animation: fadeInUp 1.8s ease-out 0.5s both;
}

.stat-number {
    animation: countUp 2s ease-out 1s both, glow 2s ease-in-out infinite 1.5s;
}

.stat-label {
    animation: fadeInUp 1.5s ease-out 1.5s both;
}

.feature-title {
    animation: slideInLeft 1s ease-out both;
}

.feature-description {
    animation: slideInLeft 1.2s ease-out 0.2s both;
}

.section-title {
    animation: fadeInUp 1s ease-out both;
}

.section-subtitle {
    animation: fadeInUp 1.2s ease-out 0.3s both;
}

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

@keyframes typewriter {
    from {
        width: 0;
    }
    to {
        width: 100%;
    }
}

@keyframes blink {
    0%, 50% {
        border-color: #8b5cf6;
    }
    51%, 100% {
        border-color: transparent;
    }
}

@keyframes countUp {
    from {
        opacity: 0;
        transform: scale(0.5);
    }
    to {
        opacity: 1;
        transform: scale(1);
    }
}

@keyframes glow {
    0%, 100% {
        text-shadow: 0 0 5px #8b5cf6, 0 0 10px #8b5cf6, 0 0 15px #8b5cf6;
    }
    50% {
        text-shadow: 0 0 10px #8b5cf6, 0 0 20px #8b5cf6, 0 0 30px #8b5cf6;
    }
}

@keyframes slideInLeft {
    from {
        opacity: 0;
        transform: translateX(-50px);
    }
    to {
        opacity: 1;
        transform: translateX(0);
    }
}