/* ========================================
   SpeakAI H5 - Modern Tech Style
   Pure CSS, No Framework, Mobile-First
   ======================================== */

/* CSS Variables - Easy to customize */
:root {
    /* Colors - Green Theme (统一 Flutter 客户端配色) */
    --primary-color: #5DBE53;        /* 主色绿 - 与 Flutter primaryColor 一致 */
    --primary-dark: #4aa944;         /* 深绿 */
    --primary-light: #7cd072;        /* 浅绿 */
    --secondary-color: #43a047;      /* 次要绿色 */
    --accent-color: #66bb6a;         /* 强调绿色 */
    --unselected-color: #9fa0a0;     /* 未选中灰色 - 与 Flutter unselectedColor 一致 */
    
    /* Gradients - 以绿色为主 */
    --gradient-primary: linear-gradient(135deg, #5DBE53 0%, #43a047 100%);
    --gradient-green: linear-gradient(135deg, #7cd072 0%, #5DBE53 100%);
    --gradient-hero: linear-gradient(135deg, #e8f5e9 0%, #c8e6c9 100%);
    
    /* Neutral Colors */
    --text-primary: #0f172a;
    --text-secondary: #64748b;
    --text-light: #94a3b8;
    --bg-white: #ffffff;
    --bg-light: #f8fafc;
    --bg-gray: #f1f5f9;
    --border-color: #e2e8f0;
    
    /* Spacing */
    --spacing-xs: 0.5rem;
    --spacing-sm: 1rem;
    --spacing-md: 1.5rem;
    --spacing-lg: 2rem;
    --spacing-xl: 3rem;
    --spacing-2xl: 4rem;
    
    /* Border Radius */
    --radius-sm: 0.5rem;
    --radius-md: 0.75rem;
    --radius-lg: 1rem;
    --radius-xl: 1.5rem;
    
    /* 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);
    --shadow-lg: 0 10px 15px -3px rgba(0, 0, 0, 0.1);
    --shadow-xl: 0 20px 25px -5px rgba(0, 0, 0, 0.1);
    
    /* Transitions */
    --transition-fast: 150ms ease;
    --transition-base: 300ms ease;
    --transition-slow: 500ms ease;
}

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

/* Body & Typography */
body {
    font-family: -apple-system, BlinkMacSystemFont, 'Segoe UI', 'Roboto', 
                 'Oxygen', 'Ubuntu', 'Cantarell', 'Fira Sans', 'Droid Sans', 
                 'Helvetica Neue', sans-serif;
    font-size: 16px;
    line-height: 1.6;
    color: var(--text-primary);
    background: var(--bg-white);
    -webkit-font-smoothing: antialiased;
    -moz-osx-font-smoothing: grayscale;
    overflow-x: hidden;
}

/* Navigation Bar */
.navbar {
    position: fixed;
    top: 0;
    left: 0;
    right: 0;
    background: rgba(255, 255, 255, 0.95);
    backdrop-filter: blur(10px);
    border-bottom: 1px solid var(--border-color);
    z-index: 1000;
    transition: all var(--transition-base);
}

.navbar.scrolled {
    box-shadow: var(--shadow-md);
}

.nav-container {
    max-width: 1200px;
    margin: 0 auto;
    padding: 1rem 1.5rem;
    display: flex;
    justify-content: space-between;
    align-items: center;
}

.nav-logo {
    display: flex;
    align-items: center;
    gap: 0.5rem;
    font-size: 1.5rem;
    font-weight: 700;
    color: var(--primary-color);
    text-decoration: none;
    transition: transform var(--transition-fast);
}

.nav-logo:hover {
    transform: scale(1.05);
}

/* Logo Image */
.logo-img {
    height: 32px;
    width: 32px;
    object-fit: contain;
    border-radius: 4px;
}

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

.nav-menu a {
    color: var(--text-primary);
    text-decoration: none;
    font-weight: 500;
    font-size: 0.95rem;
    transition: color var(--transition-fast);
    position: relative;
}

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

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

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

/* Mobile Menu Toggle */
.menu-toggle {
    display: none;
    flex-direction: column;
    gap: 4px;
    background: none;
    border: none;
    cursor: pointer;
    padding: 0.5rem;
}

.menu-toggle span {
    width: 24px;
    height: 2px;
    background: var(--text-primary);
    transition: all var(--transition-base);
}

/* Buttons */
.btn {
    display: inline-flex;
    align-items: center;
    justify-content: center;
    gap: 0.5rem;
    padding: 0.75rem 1.5rem;
    border: none;
    border-radius: var(--radius-md);
    font-size: 1rem;
    font-weight: 600;
    text-decoration: none;
    cursor: pointer;
    transition: all var(--transition-base);
    white-space: nowrap;
}

.btn-primary {
    background: var(--gradient-primary);
    color: white;
    box-shadow: var(--shadow-md);
}

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

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

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

.btn-lg {
    padding: 1rem 2rem;
    font-size: 1.125rem;
}

.btn-icon {
    padding: 0.75rem;
    width: 48px;
    height: 48px;
}

/* Icon inside button text */
.btn img.btn-icon {
    display: inline-block;
    width: 20px;
    height: 20px;
    padding: 0;
    margin-right: 0.5rem;
    vertical-align: middle;
    margin-top: -2px;
}

/* Container & Layout */
.container {
    max-width: 1200px;
    margin: 0 auto;
    padding: 0 1.5rem;
}

.section {
    padding: var(--spacing-2xl) 0;
}

.section-sm {
    padding: var(--spacing-xl) 0;
}

.section-lg {
    padding: 5rem 0;
}

/* Hero Section */
.hero {
    position: relative;
    min-height: 100vh;
    display: flex;
    align-items: center;
    justify-content: center;
    background: var(--gradient-hero);
    color: var(--text-primary);
    overflow: hidden;
    padding-top: 80px;
}

.hero::before {
    content: '';
    position: absolute;
    top: 0;
    left: 0;
    right: 0;
    bottom: 0;
    background: 
        radial-gradient(circle at 20% 50%, rgba(255,255,255,0.1) 0%, transparent 50%),
        radial-gradient(circle at 80% 80%, rgba(255,255,255,0.1) 0%, transparent 50%);
    animation: pulse 10s ease-in-out infinite;
}

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

.hero-content {
    position: relative;
    z-index: 1;
    text-align: center;
    max-width: 800px;
}

.hero h1 {
    font-size: clamp(2.5rem, 5vw, 4rem);
    font-weight: 800;
    margin-bottom: 1.5rem;
    line-height: 1.2;
    animation: fadeInUp 0.8s ease-out;
}

.hero p {
    font-size: clamp(1.125rem, 2vw, 1.5rem);
    margin-bottom: 2rem;
    opacity: 0.95;
    animation: fadeInUp 0.8s ease-out 0.2s both;
}

.hero-cta {
    display: flex;
    gap: 1rem;
    justify-content: center;
    flex-wrap: wrap;
    animation: fadeInUp 0.8s ease-out 0.4s both;
}

/* Grid Layouts */
.grid {
    display: grid;
    gap: 2rem;
}

.grid-2 {
    grid-template-columns: repeat(auto-fit, minmax(280px, 1fr));
}

.grid-3 {
    grid-template-columns: repeat(auto-fit, minmax(250px, 1fr));
}

.grid-4 {
    grid-template-columns: repeat(auto-fit, minmax(200px, 1fr));
}

/* Cards */
.card {
    background: white;
    border-radius: var(--radius-xl);
    padding: 2rem;
    box-shadow: var(--shadow-md);
    transition: all var(--transition-base);
    border: 1px solid var(--border-color);
}

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

.card-icon {
    width: 64px;
    height: 64px;
    border-radius: var(--radius-lg);
    background: var(--gradient-primary);
    display: flex;
    align-items: center;
    justify-content: center;
    font-size: 2rem;
    margin-bottom: 1.5rem;
}

.card h3 {
    font-size: 1.25rem;
    font-weight: 700;
    margin-bottom: 0.75rem;
    color: var(--text-primary);
}

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

/* Section Titles */
.section-title {
    text-align: center;
    margin-bottom: 3rem;
}

.section-title h2 {
    font-size: clamp(2rem, 4vw, 3rem);
    font-weight: 800;
    margin-bottom: 1rem;
    background: var(--gradient-primary);
    -webkit-background-clip: text;
    -webkit-text-fill-color: transparent;
    background-clip: text;
}

.section-title p {
    font-size: 1.125rem;
    color: var(--text-secondary);
    max-width: 600px;
    margin: 0 auto;
}

/* Stats Section */
.stats {
    background: var(--gradient-primary);
    color: white;
    padding: 3rem 0;
}

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

.stat-item h3 {
    font-size: 3rem;
    font-weight: 800;
    margin-bottom: 0.5rem;
}

.stat-item p {
    font-size: 1.125rem;
    opacity: 0.9;
}

/* Download Section */
.download-card {
    display: flex;
    align-items: center;
    gap: 1.5rem;
    padding: 1.5rem;
    background: white;
    border-radius: var(--radius-lg);
    border: 2px solid var(--border-color);
    transition: all var(--transition-base);
    text-decoration: none;
    color: var(--text-primary);
}

.download-card:hover {
    border-color: var(--primary-color);
    transform: translateY(-2px);
    box-shadow: var(--shadow-lg);
}

.download-icon {
    font-size: 3rem;
    display: flex;
    align-items: center;
    justify-content: center;
}

.download-icon-img {
    width: 48px;
    height: 48px;
    object-fit: contain;
}

.download-text h4 {
    font-size: 0.875rem;
    color: var(--text-secondary);
    margin-bottom: 0.25rem;
}

.download-text p {
    font-size: 1.125rem;
    font-weight: 700;
}

/* Content Page Styles */
.content-page {
    padding-top: 100px;
    padding-bottom: 4rem;
    min-height: 100vh;
}

.content-container {
    max-width: 900px;
    margin: 0 auto;
    padding: 0 1.5rem;
}

.page-title {
    font-size: clamp(2rem, 4vw, 3rem);
    font-weight: 800;
    margin-bottom: 2rem;
    text-align: center;
    background: var(--gradient-primary);
    -webkit-background-clip: text;
    -webkit-text-fill-color: transparent;
    background-clip: text;
}

.content-section {
    margin-bottom: 3rem;
}

.content-section h2 {
    font-size: 1.75rem;
    font-weight: 700;
    margin-bottom: 1rem;
    color: var(--text-primary);
    padding-bottom: 0.5rem;
    border-bottom: 3px solid var(--primary-color);
}

.content-section h3 {
    font-size: 1.375rem;
    font-weight: 600;
    margin: 1.5rem 0 1rem;
    color: var(--text-primary);
}

.content-section h4 {
    font-size: 1.125rem;
    font-weight: 600;
    margin: 1rem 0 0.75rem;
    color: var(--primary-dark);
}

.content-section p {
    margin-bottom: 1rem;
    color: var(--text-secondary);
    line-height: 1.8;
}

.content-section ul,
.content-section ol {
    margin: 1rem 0 1rem 2rem;
    color: var(--text-secondary);
}

.content-section li {
    margin-bottom: 0.75rem;
    line-height: 1.8;
}

.content-section strong {
    color: var(--text-primary);
    font-weight: 600;
}

/* Alert Boxes */
.alert {
    padding: 1.5rem;
    border-radius: var(--radius-md);
    margin: 2rem 0;
    border-left: 4px solid;
}

.alert-info {
    background: #eff6ff;
    border-color: var(--primary-color);
    color: var(--primary-dark);
}

.alert-warning {
    background: #fef3c7;
    border-color: #f59e0b;
    color: #92400e;
}

.alert-success {
    background: #d1fae5;
    border-color: var(--secondary-color);
    color: #065f46;
}

/* Footer */
.footer {
    background: var(--text-primary);
    color: white;
    padding: 3rem 0 2rem;
}

.footer-content {
    display: grid;
    grid-template-columns: repeat(auto-fit, minmax(250px, 1fr));
    gap: 2rem;
    margin-bottom: 2rem;
}

.footer-section h3 {
    font-size: 1.125rem;
    font-weight: 700;
    margin-bottom: 1rem;
}

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

.footer-section li {
    margin-bottom: 0.75rem;
}

.footer-section a {
    color: rgba(255, 255, 255, 0.8);
    text-decoration: none;
    transition: color var(--transition-fast);
}

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

.footer-bottom {
    border-top: 1px solid rgba(255, 255, 255, 0.1);
    padding-top: 2rem;
    text-align: center;
    color: rgba(255, 255, 255, 0.6);
}

.footer-bottom a {
    color: rgba(255, 255, 255, 0.8);
    text-decoration: none;
    margin: 0 0.5rem;
}

/* Back to Top Button */
.back-to-top {
    position: fixed;
    bottom: 2rem;
    right: 2rem;
    width: 48px;
    height: 48px;
    border-radius: 50%;
    background: var(--gradient-primary);
    color: white;
    border: none;
    cursor: pointer;
    opacity: 0;
    visibility: hidden;
    transition: all var(--transition-base);
    box-shadow: var(--shadow-lg);
    z-index: 999;
}

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

.back-to-top:hover {
    transform: translateY(-4px);
    box-shadow: var(--shadow-xl);
}

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

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

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

.fade-in-up {
    animation: fadeInUp 0.6s ease-out;
}

.fade-in-down {
    animation: fadeInDown 0.6s ease-out;
}

.slide-in-left {
    animation: slideInLeft 0.6s ease-out;
}

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

.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); }

.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); }

.p-1 { padding: var(--spacing-xs); }
.p-2 { padding: var(--spacing-sm); }
.p-3 { padding: var(--spacing-md); }
.p-4 { padding: var(--spacing-lg); }

/* Responsive Design */
@media (max-width: 768px) {
    .nav-menu {
        position: fixed;
        top: 0;
        left: -100%;
        width: 80%;
        height: 100vh;
        background: white;
        flex-direction: column;
        align-items: flex-start;
        padding: 5rem 2rem;
        box-shadow: var(--shadow-xl);
        transition: left var(--transition-base);
    }
    
    .nav-menu.active {
        left: 0;
    }
    
    .menu-toggle {
        display: flex;
    }
    
    .hero {
        min-height: auto;
        padding: 6rem 0 4rem;
    }
    
    .hero-cta {
        flex-direction: column;
        align-items: stretch;
    }
    
    .section {
        padding: 3rem 0;
    }
    
    .grid {
        gap: 1.5rem;
    }
    
    .stats-grid {
        grid-template-columns: repeat(2, 1fr);
    }
    
    .download-card {
        flex-direction: column;
        text-align: center;
    }
    
    .back-to-top {
        bottom: 1rem;
        right: 1rem;
    }
}

@media (max-width: 480px) {
    .nav-container {
        padding: 0.75rem 1rem;
    }
    
    .stats-grid {
        grid-template-columns: 1fr;
    }
    
    .stat-item h3 {
        font-size: 2.5rem;
    }
}

/* Dark Mode Support */
@media (prefers-color-scheme: dark) {
    :root {
        --text-primary: #f1f5f9;
        --text-secondary: #94a3b8;
        --bg-white: #0f172a;
        --bg-light: #1e293b;
        --bg-gray: #334155;
        --border-color: #334155;
    }
    
    .navbar {
        background: rgba(15, 23, 42, 0.95);
    }
    
    .card {
        background: var(--bg-light);
    }
    
    .download-card {
        background: var(--bg-light);
    }
}

/* Print Styles */
@media print {
    .navbar,
    .footer,
    .back-to-top,
    .hero-cta {
        display: none;
    }
    
    .hero {
        min-height: auto;
        padding: 2rem 0;
        background: white;
        color: black;
    }
    
    .content-page {
        padding-top: 0;
    }
}