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

:root {
    /* Color System - Light Theme */
    --primary-color: #10b981;
    --primary-hover: #059669;
    --secondary-color: #3b82f6;
    --accent-color: #8b5cf6;
    --warning-color: #f59e0b;
    --danger-color: #ef4444;
    --info-color: #06b6d4;

    /* Background Colors */
    --bg-primary: #ffffff;
    --bg-secondary: #f9fafb;
    --bg-tertiary: #f3f4f6;
    --bg-card: #ffffff;
    --bg-overlay: rgba(0, 0, 0, 0.5);

    /* Text Colors */
    --text-primary: #111827;
    --text-secondary: #6b7280;
    --text-muted: #9ca3af;
    --text-inverse: #ffffff;

    /* Border Colors */
    --border-primary: #e5e7eb;
    --border-secondary: #f3f4f6;
    
    /* Gradient Colors */
    --gradient-primary: linear-gradient(135deg, #10b981 0%, #059669 100%);
    --gradient-secondary: linear-gradient(135deg, #3b82f6 0%, #1d4ed8 100%);
    --gradient-text: linear-gradient(135deg, #10b981 0%, #3b82f6 100%);
    
    /* Typography */
    --font-family: 'Inter', 'PingFang SC', 'Hiragino Sans GB', 'Microsoft YaHei', -apple-system, BlinkMacSystemFont, 'Segoe UI', 'Roboto', sans-serif;
    --font-size-xs: 0.75rem;
    --font-size-sm: 0.875rem;
    --font-size-base: 1rem;
    --font-size-lg: 1.125rem;
    --font-size-xl: 1.25rem;
    --font-size-2xl: 1.5rem;
    --font-size-3xl: 1.875rem;
    --font-size-4xl: 2.25rem;
    --font-size-5xl: 3rem;
    --font-size-6xl: 3.75rem;
    
    /* Spacing */
    --spacing-1: 0.25rem;
    --spacing-2: 0.5rem;
    --spacing-3: 0.75rem;
    --spacing-4: 1rem;
    --spacing-5: 1.25rem;
    --spacing-6: 1.5rem;
    --spacing-8: 2rem;
    --spacing-10: 2.5rem;
    --spacing-12: 3rem;
    --spacing-16: 4rem;
    --spacing-20: 5rem;
    
    /* Border Radius */
    --radius-sm: 0.375rem;
    --radius-md: 0.5rem;
    --radius-lg: 0.75rem;
    --radius-xl: 1rem;
    --radius-2xl: 1.5rem;
    --radius-full: 9999px;
    
    /* Shadows */
    --shadow-sm: 0 1px 3px 0 rgba(0, 0, 0, 0.1), 0 1px 2px 0 rgba(0, 0, 0, 0.06);
    --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);
    --shadow-glow: 0 0 0 2px rgba(16, 185, 129, 0.2), 0 0 25px rgba(16, 185, 129, 0.15);
    
    /* Transitions */
    --transition-fast: 0.15s ease-out;
    --transition-normal: 0.3s ease-out;
    --transition-slow: 0.5s ease-out;
    
    /* Z-index */
    --z-dropdown: 1000;
    --z-sticky: 1020;
    --z-fixed: 1030;
    --z-modal-backdrop: 1040;
    --z-modal: 1050;
    --z-popover: 1060;
    --z-tooltip: 1070;
}

html {
    scroll-behavior: smooth;
}

body {
    font-family: var(--font-family);
    font-size: var(--font-size-base);
    line-height: 1.6;
    color: var(--text-primary);
    background-color: var(--bg-primary);
    overflow-x: hidden;
}

/* Container */
.container {
    max-width: 1200px;
    margin: 0 auto;
    padding: 0 var(--spacing-6);
}

@media (max-width: 768px) {
    .container {
        padding: 0 var(--spacing-4);
    }
}

/* Navigation */
.navbar {
    position: fixed;
    top: 0;
    left: 0;
    right: 0;
    background: rgba(255, 255, 255, 0.95);
    backdrop-filter: blur(20px);
    border-bottom: 1px solid var(--border-secondary);
    z-index: var(--z-fixed);
    transition: all var(--transition-normal);
}

.navbar .container {
    display: flex;
    justify-content: space-between;
    align-items: center;
    padding-top: var(--spacing-4);
    padding-bottom: var(--spacing-4);
}

.nav-brand {
    display: flex;
    align-items: center;
    gap: var(--spacing-3);
}

.nav-brand .brand-logo {
    height: 32px;
    width: auto;
    object-fit: contain;
}

.nav-brand .brand-text {
    font-size: var(--font-size-2xl);
    font-weight: 700;
    background: var(--gradient-text);
    -webkit-background-clip: text;
    -webkit-text-fill-color: transparent;
    background-clip: text;
}

.nav-menu {
    display: flex;
    align-items: center;
    gap: var(--spacing-6);
}

.language-toggle {
    display: flex;
    gap: var(--spacing-2);
}

.lang-btn {
    padding: var(--spacing-2) var(--spacing-4);
    background: transparent;
    border: 1px solid var(--border-primary);
    border-radius: var(--radius-md);
    color: var(--text-secondary);
    font-size: var(--font-size-sm);
    cursor: pointer;
    transition: all var(--transition-fast);
}

.lang-btn.active,
.lang-btn:hover {
    background: var(--primary-color);
    border-color: var(--primary-color);
    color: white;
}

/* Hero Section */
.hero {
    padding: calc(80px + var(--spacing-20)) 0 var(--spacing-20);
    background:
        radial-gradient(ellipse at top left, rgba(16, 185, 129, 0.05) 0%, transparent 50%),
        radial-gradient(ellipse at bottom right, rgba(59, 130, 246, 0.05) 0%, transparent 50%),
        var(--bg-primary);
    position: relative;
    overflow: hidden;
}

.hero::before {
    content: '';
    position: absolute;
    top: 0;
    left: 0;
    right: 0;
    bottom: 0;
    background-image: 
        radial-gradient(circle at 25% 25%, rgba(16, 185, 129, 0.05) 0%, transparent 50%),
        radial-gradient(circle at 75% 75%, rgba(59, 130, 246, 0.05) 0%, transparent 50%);
    animation: float 20s ease-in-out infinite;
}

@keyframes float {
    0%, 100% { transform: translateY(0px) rotate(0deg); }
    50% { transform: translateY(-20px) rotate(1deg); }
}

.hero .container {
    display: grid;
    grid-template-columns: 1fr 1fr;
    gap: var(--spacing-16);
    align-items: center;
    position: relative;
    z-index: 1;
}

.hero-content {
    max-width: 600px;
}

.hero-title {
    font-size: var(--font-size-5xl);
    font-weight: 700;
    line-height: 1.1;
    margin-bottom: var(--spacing-6);
}

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

.hero-subtitle {
    font-size: var(--font-size-xl);
    color: var(--text-secondary);
    margin-bottom: var(--spacing-8);
    line-height: 1.5;
}

.hero-cta {
    display: flex;
    gap: var(--spacing-4);
    align-items: center;
}

.cta-primary {
    display: flex;
    align-items: center;
    gap: var(--spacing-2);
    padding: var(--spacing-4) var(--spacing-8);
    background: var(--gradient-primary);
    border: none;
    border-radius: var(--radius-xl);
    color: white;
    font-size: var(--font-size-lg);
    font-weight: 600;
    cursor: pointer;
    transition: all var(--transition-normal);
    box-shadow: var(--shadow-lg);
}

.cta-primary:hover {
    transform: translateY(-2px);
    box-shadow: var(--shadow-xl), var(--shadow-glow);
}


/* Hero Visual */
.hero-visual {
    position: relative;
    display: flex;
    justify-content: center;
    align-items: center;
}

.phone-mockup {
    width: 300px;
    height: 600px;
    background: var(--bg-secondary);
    border-radius: 30px;
    padding: 20px;
    box-shadow: var(--shadow-xl);
    position: relative;
    border: 3px solid var(--border-primary);
}

.phone-content {
    width: 100%;
    height: 100%;
    background: var(--bg-primary);
    border-radius: 20px;
    overflow: hidden;
    position: relative;
}

/* 首页app截图容器样式 */
.hero-app-screenshot-container {
    position: absolute;
    top: 0;
    left: 0;
    width: 100%;
    height: 100%;
    z-index: 2;
}

.hero-app-screenshot {
    width: 100%;
    height: 100%;
    object-fit: cover;
    border-radius: 20px;
}

.app-preview {
    height: 100%;
    display: flex;
    flex-direction: column;
}

.preview-header {
    padding: var(--spacing-4);
    border-bottom: 1px solid var(--border-secondary);
}

.status-bar {
    display: flex;
    justify-content: space-between;
    align-items: center;
    color: var(--text-primary);
    font-weight: 600;
}

.preview-body {
    flex: 1;
    padding: var(--spacing-6);
    display: flex;
    flex-direction: column;
    gap: var(--spacing-6);
}

.calorie-ring {
    display: flex;
    justify-content: center;
    align-items: center;
    height: 200px;
}

.ring-progress {
    width: 160px;
    height: 160px;
    border-radius: 50%;
    background: conic-gradient(var(--primary-color) 0deg 216deg, var(--bg-tertiary) 216deg 360deg);
    padding: 20px;
    display: flex;
    justify-content: center;
    align-items: center;
}

.ring-center {
    width: 100%;
    height: 100%;
    background: var(--bg-primary);
    border-radius: 50%;
    display: flex;
    flex-direction: column;
    justify-content: center;
    align-items: center;
    text-align: center;
}

.calories-left {
    font-size: var(--font-size-2xl);
    font-weight: 700;
    color: var(--text-primary);
}

.calories-unit {
    font-size: var(--font-size-sm);
    color: var(--text-secondary);
}

.meal-summary {
    display: flex;
    flex-direction: column;
    gap: var(--spacing-4);
}

.meal-item {
    display: flex;
    justify-content: space-between;
    align-items: center;
    padding: var(--spacing-3) var(--spacing-4);
    background: var(--bg-card);
    border-radius: var(--radius-lg);
    font-size: var(--font-size-sm);
}

/* Floating Elements */
.floating-elements {
    position: absolute;
    top: 50%;
    left: 50%;
    transform: translate(-50%, -50%);
    pointer-events: none;
}

.float-card {
    position: absolute;
    display: flex;
    align-items: center;
    gap: var(--spacing-2);
    padding: var(--spacing-3) var(--spacing-4);
    background: var(--bg-card);
    border-radius: var(--radius-lg);
    font-size: var(--font-size-sm);
    font-weight: 500;
    box-shadow: var(--shadow-lg);
    animation: floating 3s ease-in-out infinite;
    border: 1px solid var(--border-primary);
}

.ai-card {
    top: -80px;
    left: -120px;
    animation-delay: 0s;
}

.nutrition-card {
    bottom: -80px;
    right: -120px;
    animation-delay: 1.5s;
}

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

/* Features Section */
.features {
    padding: var(--spacing-20) 0;
    background: var(--bg-secondary);
}

.section-header {
    text-align: center;
    margin-bottom: var(--spacing-16);
}

.section-title {
    font-size: var(--font-size-4xl);
    font-weight: 700;
    margin-bottom: var(--spacing-4);
}

.section-subtitle {
    font-size: var(--font-size-xl);
    color: var(--text-secondary);
    max-width: 600px;
    margin: 0 auto;
}

.features-grid {
    display: grid;
    grid-template-columns: repeat(auto-fit, minmax(350px, 1fr));
    gap: var(--spacing-6);
    margin-top: var(--spacing-12);
}

.feature-card {
    padding: var(--spacing-8);
    background: var(--bg-card);
    border-radius: var(--radius-xl);
    border: 1px solid var(--border-secondary);
    transition: all var(--transition-normal);
    position: relative;
    overflow: hidden;
}

.feature-card.primary {
    border-color: var(--primary-color);
    background: linear-gradient(135deg, rgba(16, 185, 129, 0.05) 0%, var(--bg-card) 100%);
}

.feature-card:hover {
    transform: translateY(-4px);
    box-shadow: var(--shadow-xl);
    border-color: var(--primary-color);
}

.feature-icon {
    width: 60px;
    height: 60px;
    background: var(--bg-tertiary);
    border-radius: var(--radius-lg);
    display: flex;
    justify-content: center;
    align-items: center;
    margin-bottom: var(--spacing-6);
}

.feature-title {
    font-size: var(--font-size-xl);
    font-weight: 600;
    margin-bottom: var(--spacing-4);
}

.feature-description {
    color: var(--text-secondary);
    line-height: 1.6;
}

/* AI Showcase Section */
.ai-showcase {
    padding: var(--spacing-20) 0;
    background: var(--bg-primary);
}

.showcase-content {
    display: grid;
    grid-template-columns: 1fr 1fr;
    gap: var(--spacing-16);
    align-items: center;
}

.showcase-title {
    font-size: var(--font-size-4xl);
    font-weight: 700;
    margin-bottom: var(--spacing-6);
}

.showcase-description {
    font-size: var(--font-size-lg);
    color: var(--text-secondary);
    margin-bottom: var(--spacing-8);
    line-height: 1.6;
}

.showcase-stats {
    display: grid;
    grid-template-columns: repeat(3, 1fr);
    gap: var(--spacing-6);
}

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

.stat-number {
    display: block;
    font-size: var(--font-size-3xl);
    font-weight: 700;
    color: var(--primary-color);
    margin-bottom: var(--spacing-2);
}

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

.ai-demo {
    display: flex;
    flex-direction: column;
    gap: var(--spacing-8);
}

.demo-steps {
    display: flex;
    justify-content: space-between;
    align-items: center;
}

.step-item {
    display: flex;
    flex-direction: column;
    align-items: center;
    gap: var(--spacing-2);
}

.step-item.active .step-number {
    background: var(--primary-color);
    color: white;
}

.step-number {
    width: 40px;
    height: 40px;
    border-radius: 50%;
    background: var(--bg-tertiary);
    color: var(--text-secondary);
    display: flex;
    justify-content: center;
    align-items: center;
    font-weight: 600;
    transition: all var(--transition-normal);
}

.step-arrow {
    width: 40px;
    height: 2px;
    background: var(--border-primary);
    position: relative;
}

.step-arrow::after {
    content: '';
    position: absolute;
    right: -6px;
    top: -3px;
    width: 0;
    height: 0;
    border-left: 6px solid var(--border-primary);
    border-top: 4px solid transparent;
    border-bottom: 4px solid transparent;
}

.demo-visual {
    margin-top: var(--spacing-8);
}

.demo-screenshots {
    display: flex;
    justify-content: space-between;
    align-items: center;
    width: 100%;
}

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

.screenshot-placeholder {
    width: 120px;
    height: 200px;
    border-radius: var(--radius-lg);
    background: var(--bg-card);
    display: flex;
    justify-content: center;
    align-items: center;
    border: 2px solid var(--border-secondary);
    overflow: hidden;
    transition: all var(--transition-normal);
}

.screenshot-placeholder:hover {
    transform: translateY(-4px);
    box-shadow: var(--shadow-lg);
    border-color: var(--primary-color);
}

.demo-screenshot {
    width: 100%;
    height: 100%;
    object-fit: cover;
}

/* Download Section */
.download {
    padding: var(--spacing-20) 0;
    background: var(--bg-secondary);
}

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

.download-title {
    font-size: var(--font-size-4xl);
    font-weight: 700;
    margin-bottom: var(--spacing-4);
}

.download-subtitle {
    font-size: var(--font-size-xl);
    color: var(--text-secondary);
    margin-bottom: var(--spacing-12);
}

.download-options {
    display: grid;
    grid-template-columns: 1fr 1fr;
    gap: var(--spacing-8);
    max-width: 800px;
    min-height: 332px;
    margin: 0 auto;
}

.download-option {
    padding: var(--spacing-8);
    background: var(--bg-card);
    border-radius: var(--radius-xl);
    border: 2px solid var(--border-secondary);
    transition: all var(--transition-normal);
}

.download-option.primary {
    border-color: var(--primary-color);
    background: linear-gradient(135deg, rgba(16, 185, 129, 0.05) 0%, var(--bg-card) 100%);
}

.download-option:hover {
    transform: translateY(-4px);
    box-shadow: var(--shadow-xl);
}

.download-option.primary .download-icon svg {
    animation: pulse 2s ease-in-out infinite;
}

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

.download-info h3 {
    font-size: var(--font-size-xl);
    font-weight: 600;
    margin-bottom: var(--spacing-2);
}

.download-info p {
    color: var(--text-secondary);
    margin-bottom: var(--spacing-6);
}

.qr-code {
    display: flex;
    justify-content: center;
}

.qr-placeholder {
    padding: var(--spacing-4);
    background: white;
    border-radius: var(--radius-lg);
}

.download-platforms {
    display: flex;
    flex-direction: column;
    gap: var(--spacing-4);
}

.platform-btn {
    display: flex;
    align-items: center;
    gap: var(--spacing-4);
    padding: var(--spacing-4) var(--spacing-6);
    background: var(--bg-tertiary);
    border-radius: var(--radius-lg);
    text-decoration: none;
    color: var(--text-primary);
    transition: all var(--transition-normal);
    border: 1px solid var(--border-primary);
}

.platform-btn:hover {
    background: var(--bg-secondary);
    border-color: var(--primary-color);
}

.platform-icon {
    width: 40px;
    height: 40px;
    display: flex;
    justify-content: center;
    align-items: center;
    background: var(--bg-card);
    border-radius: var(--radius-md);
}

.platform-btn div span {
    display: block;
    font-weight: 600;
    margin-bottom: var(--spacing-1);
}

.platform-btn div small {
    color: var(--text-secondary);
    font-size: var(--font-size-sm);
}

/* Footer */
.footer {
    padding: var(--spacing-16) 0 var(--spacing-8);
    background: var(--bg-primary);
    border-top: 1px solid var(--border-secondary);
}

.footer-content {
    display: grid;
    grid-template-columns: 1fr 2fr;
    gap: var(--spacing-12);
    margin-bottom: var(--spacing-8);
}

.footer-brand h3 {
    font-size: var(--font-size-2xl);
    font-weight: 700;
    background: var(--gradient-text);
    -webkit-background-clip: text;
    -webkit-text-fill-color: transparent;
    background-clip: text;
    margin-bottom: var(--spacing-2);
}

.footer-brand p {
    color: var(--text-secondary);
}

.footer-links {
    display: grid;
    grid-template-columns: repeat(3, 1fr);
    gap: var(--spacing-8);
}

.footer-column h4 {
    font-size: var(--font-size-lg);
    font-weight: 600;
    margin-bottom: var(--spacing-4);
}

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

.footer-column li {
    margin-bottom: var(--spacing-2);
}

.footer-column a {
    color: var(--text-secondary);
    text-decoration: none;
    transition: color var(--transition-fast);
}

.footer-column a:hover {
    color: var(--primary-color);
}

.footer-bottom {
    padding-top: var(--spacing-8);
    border-top: 1px solid var(--border-secondary);
    text-align: center;
    color: var(--text-muted);
}

/* Responsive Design */
@media (max-width: 1024px) {
    .hero .container {
        grid-template-columns: 1fr;
        gap: var(--spacing-12);
        text-align: center;
    }
    
    .showcase-content {
        grid-template-columns: 1fr;
        gap: var(--spacing-12);
        text-align: center;
    }
    
    .download-options {
        grid-template-columns: 1fr;
    }
    
    .footer-content {
        grid-template-columns: 1fr;
        gap: var(--spacing-8);
    }
    
    .footer-links {
        grid-template-columns: repeat(2, 1fr);
    }

    .demo-screenshots {
        gap: var(--spacing-4);
    }

    .screenshot-placeholder {
        width: 100px;
        height: 160px;
    }
}

@media (max-width: 768px) {
    .hero {
        padding: calc(80px + var(--spacing-12)) 0 var(--spacing-12);
    }
    
    .hero-title {
        font-size: var(--font-size-4xl);
    }
    
    .hero-subtitle {
        font-size: var(--font-size-lg);
    }
    
    .hero-cta {
        flex-direction: column;
        align-items: stretch;
    }
    
    .cta-primary,
    .cta-secondary {
        justify-content: center;
    }
    
    .phone-mockup {
        width: 250px;
        height: 500px;
        padding: 15px;
    }
    
    .floating-elements {
        display: none;
    }
    
    .features-grid {
        grid-template-columns: 1fr;
    }

    .demo-screenshots {
        flex-direction: column;
        gap: var(--spacing-4);
        margin-top: var(--spacing-6);
    }

    .screenshot-placeholder {
        width: 80px;
        height: 140px;
    }

    .demo-steps {
        flex-direction: column;
        gap: var(--spacing-4);
    }

    .step-arrow {
        display: none;
    }

    .ai-demo {
        gap: var(--spacing-6);
    }
    
    .section-title {
        font-size: var(--font-size-3xl);
    }
    
    .showcase-title {
        font-size: var(--font-size-3xl);
    }
    
    .showcase-stats {
        grid-template-columns: 1fr;
        gap: var(--spacing-4);
    }
    
    .demo-steps {
        flex-direction: column;
        gap: var(--spacing-4);
    }
    
    .step-arrow {
        transform: rotate(90deg);
        width: 20px;
    }
    
    .download-title {
        font-size: var(--font-size-3xl);
    }
    
    .footer-links {
        grid-template-columns: 1fr;
    }
}

@media (max-width: 480px) {
    .container {
        padding: 0 var(--spacing-3);
    }
    
    .navbar .container {
        padding-top: var(--spacing-3);
        padding-bottom: var(--spacing-3);
    }
    
    .nav-brand .brand-logo {
        height: 28px;
    }

    .nav-brand .brand-text {
        font-size: var(--font-size-xl);
    }
    
    .hero-title {
        font-size: var(--font-size-3xl);
    }
    
    .phone-mockup {
        width: 200px;
        height: 400px;
        padding: 10px;
    }
    
    .ring-progress {
        width: 120px;
        height: 120px;
        padding: 15px;
    }
    
    .calories-left {
        font-size: var(--font-size-xl);
    }
    
    .feature-card {
        padding: var(--spacing-6);
    }
    
    .features-grid {
        grid-template-columns: 1fr;
        margin-top: var(--spacing-8);
    }
}

/* Animations and Interactions */
@media (prefers-reduced-motion: no-preference) {
    .feature-card {
        transition: all var(--transition-normal);
    }
    
    .feature-card:hover {
        transform: translateY(-4px);
    }
    
    .cta-primary:hover {
        transform: translateY(-2px);
    }
    
    .platform-btn:hover {
        transform: translateY(-2px);
    }
}

/* Accessibility */
@media (prefers-reduced-motion: reduce) {
    * {
        animation-duration: 0.01ms !important;
        animation-iteration-count: 1 !important;
        transition-duration: 0.01ms !important;
    }
}

/* High contrast mode support */
@media (prefers-contrast: high) {
    :root {
        --border-primary: #ffffff;
        --border-secondary: #ffffff;
        --text-secondary: #ffffff;
    }
}

/* Focus styles for accessibility */
.cta-primary:focus,
.cta-secondary:focus,
.lang-btn:focus,
.platform-btn:focus {
    outline: 2px solid var(--primary-color);
    outline-offset: 2px;
}

/* Print styles */
@media print {
    .navbar,
    .floating-elements,
    .hero-cta,
    .download {
        display: none;
    }
    
    .hero {
        padding: var(--spacing-8) 0;
    }
    
    * {
        background: white !important;
        color: black !important;
    }
}