/* ===========================
   CSS Variables & Reset
   =========================== */
:root {
    /* Colors */
    --primary: #1A8CFF;
    --secondary: #8819FF;
    --accent: #00D4EB;
    --success: #1AFF88;
    --warning: #FFD700;
    --danger: #FF4458;
    --background-light: #F8FAFB;
    --background-dark: #0F1419;
    --text-primary: #1F2937;
    --text-secondary: #6B7280;
    --text-light: #9CA3AF;
    --white: #FFFFFF;
    --border: #E5E7EB;
    
    /* Spacing */
    --spacing-xs: 0.5rem;
    --spacing-sm: 1rem;
    --spacing-md: 1.5rem;
    --spacing-lg: 2rem;
    --spacing-xl: 3rem;
    --spacing-2xl: 4rem;
    --spacing-3xl: 6rem;
    
    /* Typography */
    --font-family: 'Inter', -apple-system, BlinkMacSystemFont, 'Segoe UI', 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: 2rem;
    --font-size-4xl: 2.5rem;
    --font-size-5xl: 3rem;
    
    /* Effects */
    --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);
    --shadow-2xl: 0 25px 50px -12px rgba(0, 0, 0, 0.25);
    
    /* Border Radius */
    --radius-sm: 0.375rem;
    --radius-md: 0.5rem;
    --radius-lg: 0.75rem;
    --radius-xl: 1rem;
    --radius-2xl: 1.5rem;
    --radius-full: 9999px;
    
    /* Transitions */
    --transition-fast: 150ms ease;
    --transition-base: 250ms ease;
    --transition-slow: 350ms ease;
}

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

html {
    scroll-behavior: smooth;
}

@media (prefers-reduced-motion: reduce) {
    html {
        scroll-behavior: auto;
    }
    
    *,
    *::before,
    *::after {
        animation-duration: 0.01ms !important;
        animation-iteration-count: 1 !important;
        transition-duration: 0.01ms !important;
    }
}

body {
    font-family: var(--font-family);
    font-size: var(--font-size-base);
    line-height: 1.6;
    color: var(--text-primary);
    background-color: var(--white);
    overflow-x: hidden;
    -webkit-font-smoothing: antialiased;
    -moz-osx-font-smoothing: grayscale;
}

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

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

button {
    border: none;
    background: none;
    cursor: pointer;
    font-family: inherit;
}

ul {
    list-style: none;
}

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

.gradient-text {
    background: linear-gradient(135deg, var(--primary) 0%, var(--secondary) 100%);
    -webkit-background-clip: text;
    -webkit-text-fill-color: transparent;
    background-clip: text;
}

/* ===========================
   Navigation
   =========================== */
.nav {
    position: fixed;
    top: 0;
    left: 0;
    right: 0;
    background: rgba(255, 255, 255, 0.9);
    backdrop-filter: blur(10px);
    -webkit-backdrop-filter: blur(10px);
    box-shadow: var(--shadow-sm);
    z-index: 1000;
    transition: transform var(--transition-base);
}

.nav.hidden {
    transform: translateY(-100%);
}

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

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

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

.nav-toggle {
    display: none;
    flex-direction: column;
    gap: 4px;
    width: 30px;
    height: 30px;
    padding: 5px;
}

.nav-toggle span {
    display: block;
    width: 100%;
    height: 2px;
    background: var(--text-primary);
    transition: var(--transition-base);
}

.nav-toggle.active span:nth-child(1) {
    transform: translateY(6px) rotate(45deg);
}

.nav-toggle.active span:nth-child(2) {
    opacity: 0;
}

.nav-toggle.active span:nth-child(3) {
    transform: translateY(-6px) rotate(-45deg);
}

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

.nav-links a {
    font-weight: 500;
    color: var(--text-primary);
    transition: color var(--transition-base);
    position: relative;
}

.nav-links a:not(.nav-cta):hover {
    color: var(--primary);
}

.nav-links a:not(.nav-cta)::after {
    content: '';
    position: absolute;
    bottom: -5px;
    left: 0;
    width: 0;
    height: 2px;
    background: linear-gradient(90deg, var(--primary), var(--secondary));
    transition: width var(--transition-base);
}

.nav-links a:not(.nav-cta):hover::after {
    width: 100%;
}

.nav-cta {
    padding: var(--spacing-xs) var(--spacing-md);
    background: linear-gradient(135deg, var(--primary), var(--secondary));
    color: var(--white) !important;
    border-radius: var(--radius-full);
    font-weight: 600;
    transition: transform var(--transition-base), box-shadow var(--transition-base);
}

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

/* ===========================
   Buttons
   =========================== */
.btn {
    display: inline-flex;
    align-items: center;
    justify-content: center;
    gap: var(--spacing-xs);
    padding: var(--spacing-sm) var(--spacing-lg);
    border-radius: var(--radius-full);
    font-weight: 600;
    font-size: var(--font-size-base);
    transition: all var(--transition-base);
    cursor: pointer;
    border: none;
    text-decoration: none;
    min-height: 44px;
}

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

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

.btn-primary:active {
    transform: translateY(0);
}

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

.btn-secondary:hover {
    border-color: var(--primary);
    color: var(--primary);
    box-shadow: var(--shadow-md);
}

.btn-lg {
    padding: var(--spacing-md) var(--spacing-xl);
    font-size: var(--font-size-lg);
}

.btn-xl {
    padding: var(--spacing-md) var(--spacing-2xl);
    font-size: var(--font-size-xl);
}

/* ===========================
   Hero Section
   =========================== */
.hero {
    position: relative;
    min-height: 100vh;
    display: flex;
    align-items: center;
    padding: var(--spacing-3xl) 0;
    overflow: hidden;
}

.hero-background {
    position: absolute;
    top: 0;
    left: 0;
    right: 0;
    bottom: 0;
    z-index: -1;
}

.hero-gradient {
    position: absolute;
    top: 0;
    left: 0;
    right: 0;
    bottom: 0;
    background: linear-gradient(135deg, 
        rgba(26, 140, 255, 0.05) 0%, 
        rgba(136, 25, 255, 0.05) 50%,
        rgba(0, 212, 235, 0.05) 100%);
    animation: gradientShift 15s ease infinite;
}

@keyframes gradientShift {
    0%, 100% { opacity: 1; }
    50% { opacity: 0.7; }
}

.circuit-pattern {
    position: absolute;
    top: 0;
    left: 0;
    right: 0;
    bottom: 0;
    background-image: 
        linear-gradient(90deg, var(--border) 1px, transparent 1px),
        linear-gradient(var(--border) 1px, transparent 1px);
    background-size: 50px 50px;
    opacity: 0.3;
    animation: patternMove 20s linear infinite;
}

@keyframes patternMove {
    0% { transform: translate(0, 0); }
    100% { transform: translate(50px, 50px); }
}

.hero-container {
    display: grid;
    grid-template-columns: 1fr 1fr;
    gap: var(--spacing-3xl);
    align-items: center;
}

.hero-content {
    z-index: 1;
}

.hero-title {
    font-size: var(--font-size-5xl);
    font-weight: 800;
    line-height: 1.2;
    margin-bottom: var(--spacing-md);
    animation: fadeInUp 0.8s ease;
}

.hero-subtitle {
    font-size: var(--font-size-xl);
    color: var(--text-secondary);
    margin-bottom: var(--spacing-xl);
    max-width: 550px;
    animation: fadeInUp 0.8s ease 0.2s backwards;
}

.hero-cta {
    display: flex;
    gap: var(--spacing-md);
    flex-wrap: wrap;
    animation: fadeInUp 0.8s ease 0.4s backwards;
}

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

.hero-visual {
    position: relative;
    display: flex;
    flex-direction: column;
    align-items: center;
    gap: var(--spacing-lg);
    animation: fadeInUp 0.8s ease 0.6s backwards;
}

.card-stack {
    position: relative;
    width: 100%;
    max-width: 400px;
    height: 500px;
    perspective: 1000px;
}

.demo-card {
    position: absolute;
    top: 50%;
    left: 50%;
    transform: translate(-50%, -50%);
    width: 90%;
    height: 400px;
    background: var(--white);
    border-radius: var(--radius-2xl);
    box-shadow: var(--shadow-2xl);
    padding: var(--spacing-xl);
    cursor: grab;
    user-select: none;
    transition: transform var(--transition-slow), box-shadow var(--transition-slow);
}

.demo-card:active {
    cursor: grabbing;
}

.card-1 {
    z-index: 3;
    animation: cardFloat 3s ease-in-out infinite;
}

.card-2 {
    z-index: 2;
    transform: translate(-50%, -50%) scale(0.95) translateY(20px);
    opacity: 0.7;
}

.card-3 {
    z-index: 1;
    transform: translate(-50%, -50%) scale(0.9) translateY(40px);
    opacity: 0.4;
}

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

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

.card-theme {
    font-weight: 700;
    font-size: var(--font-size-lg);
    color: var(--primary);
}

.card-difficulty {
    padding: 4px 12px;
    border-radius: var(--radius-full);
    font-size: var(--font-size-sm);
    font-weight: 600;
    text-transform: uppercase;
}

.card-difficulty.easy {
    background: rgba(26, 255, 136, 0.2);
    color: #0D8B4D;
}

.card-difficulty.medium {
    background: rgba(255, 165, 0, 0.2);
    color: #CC7000;
}

.card-difficulty.hard {
    background: rgba(255, 68, 88, 0.2);
    color: #CC1A2F;
}

.card-question {
    font-size: var(--font-size-lg);
    line-height: 1.6;
    color: var(--text-primary);
}

.swipe-indicators {
    position: absolute;
    top: 50%;
    left: 0;
    right: 0;
    transform: translateY(-50%);
    display: flex;
    justify-content: space-between;
    padding: 0 var(--spacing-md);
    pointer-events: none;
}

.swipe-left,
.swipe-right {
    opacity: 0;
    transition: opacity var(--transition-fast);
}

.demo-card:hover .swipe-left,
.demo-card:hover .swipe-right {
    animation: pulse 1.5s ease infinite;
}

@keyframes pulse {
    0%, 100% { opacity: 0.3; }
    50% { opacity: 0.7; }
}

.swipe-hint {
    display: flex;
    align-items: center;
    gap: var(--spacing-sm);
    color: var(--text-light);
    font-size: var(--font-size-sm);
    font-weight: 600;
    animation: bounce 2s ease infinite;
}

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

.swipe-arrow {
    font-size: var(--font-size-xl);
    font-weight: 700;
}

.swipe-arrow.left {
    color: var(--danger);
    animation: slideLeft 1.5s ease infinite;
}

.swipe-arrow.right {
    color: var(--success);
    animation: slideRight 1.5s ease infinite;
}

@keyframes slideLeft {
    0%, 100% { transform: translateX(0); }
    50% { transform: translateX(-5px); }
}

@keyframes slideRight {
    0%, 100% { transform: translateX(0); }
    50% { transform: translateX(5px); }
}

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

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

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

.section-subtitle {
    font-size: var(--font-size-xl);
    color: var(--text-secondary);
}

/* ===========================
   Features Section
   =========================== */
.features {
    background: var(--background-light);
}

.features-grid {
    display: grid;
    grid-template-columns: repeat(auto-fit, minmax(320px, 1fr));
    gap: var(--spacing-xl);
}

.feature-card {
    background: var(--white);
    border-radius: var(--radius-xl);
    padding: var(--spacing-xl);
    box-shadow: var(--shadow-md);
    transition: transform var(--transition-base), box-shadow var(--transition-base);
    opacity: 0;
    transform: translateY(30px);
}

.feature-card.visible {
    animation: fadeInUp 0.6s ease forwards;
}

.feature-card:hover {
    transform: translateY(-5px);
    box-shadow: var(--shadow-xl);
}

.feature-icon {
    width: 80px;
    height: 80px;
    display: flex;
    align-items: center;
    justify-content: center;
    border-radius: var(--radius-xl);
    background: linear-gradient(135deg, rgba(26, 140, 255, 0.1), rgba(136, 25, 255, 0.1));
    margin-bottom: var(--spacing-md);
}

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

.feature-description {
    color: var(--text-secondary);
    line-height: 1.7;
    margin-bottom: var(--spacing-md);
}

.feature-visual {
    margin-top: var(--spacing-md);
}

.mini-card-demo {
    height: 100px;
    display: flex;
    align-items: center;
    justify-content: center;
}

.mini-card {
    width: 80%;
    height: 80px;
    background: linear-gradient(135deg, var(--primary), var(--secondary));
    border-radius: var(--radius-md);
    animation: miniCardSwipe 3s ease infinite;
}

@keyframes miniCardSwipe {
    0%, 100% { transform: translateX(0) rotate(0deg); }
    25% { transform: translateX(-10px) rotate(-5deg); }
    75% { transform: translateX(10px) rotate(5deg); }
}

.offline-indicator {
    display: inline-flex;
    align-items: center;
    gap: var(--spacing-xs);
    padding: var(--spacing-xs) var(--spacing-md);
    background: rgba(0, 212, 235, 0.1);
    border-radius: var(--radius-full);
    color: var(--accent);
    font-weight: 600;
    font-size: var(--font-size-sm);
}

.pulse {
    width: 8px;
    height: 8px;
    background: var(--accent);
    border-radius: 50%;
    animation: pulseGrow 2s ease infinite;
}

@keyframes pulseGrow {
    0%, 100% { transform: scale(1); opacity: 1; }
    50% { transform: scale(1.5); opacity: 0.5; }
}

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

.progress-bar {
    height: 8px;
    background: var(--border);
    border-radius: var(--radius-full);
    overflow: hidden;
    position: relative;
}

.progress-bar::after {
    content: '';
    position: absolute;
    top: 0;
    left: 0;
    height: 100%;
    width: var(--progress);
    background: var(--color);
    border-radius: var(--radius-full);
    animation: progressFill 2s ease forwards;
}

@keyframes progressFill {
    from { width: 0; }
    to { width: var(--progress); }
}

.theme-grid-mini {
    display: grid;
    grid-template-columns: repeat(2, 1fr);
    gap: var(--spacing-xs);
}

.theme-mini {
    aspect-ratio: 1;
    border-radius: var(--radius-sm);
    animation: themePulse 2s ease infinite;
}

.theme-mini:nth-child(1) { animation-delay: 0s; }
.theme-mini:nth-child(2) { animation-delay: 0.2s; }
.theme-mini:nth-child(3) { animation-delay: 0.4s; }
.theme-mini:nth-child(4) { animation-delay: 0.6s; }

@keyframes themePulse {
    0%, 100% { opacity: 1; transform: scale(1); }
    50% { opacity: 0.7; transform: scale(0.95); }
}

.daily-badge {
    display: inline-flex;
    align-items: center;
    gap: var(--spacing-xs);
    padding: var(--spacing-sm) var(--spacing-md);
    background: linear-gradient(135deg, rgba(255, 215, 0, 0.2), rgba(255, 165, 0, 0.2));
    border-radius: var(--radius-full);
    font-weight: 600;
    color: #CC7000;
}

.star {
    animation: starRotate 2s linear infinite;
}

@keyframes starRotate {
    from { transform: rotate(0deg); }
    to { transform: rotate(360deg); }
}

.search-demo input {
    width: 100%;
    padding: var(--spacing-sm) var(--spacing-md);
    border: 2px solid var(--border);
    border-radius: var(--radius-full);
    font-size: var(--font-size-sm);
    transition: border-color var(--transition-base);
}

.search-demo input:focus {
    outline: none;
    border-color: var(--primary);
}

/* ===========================
   Themes Showcase Section
   =========================== */
.themes {
    background: var(--white);
}

.themes-carousel {
    position: relative;
    overflow: hidden;
    padding: var(--spacing-lg) 0;
}

.themes-track {
    display: flex;
    gap: var(--spacing-lg);
    overflow-x: auto;
    scroll-behavior: smooth;
    scrollbar-width: none;
    -ms-overflow-style: none;
    padding: var(--spacing-sm);
}

.themes-track::-webkit-scrollbar {
    display: none;
}

.theme-card {
    flex: 0 0 280px;
    background: var(--white);
    border-radius: var(--radius-xl);
    padding: var(--spacing-xl);
    box-shadow: var(--shadow-md);
    cursor: pointer;
    transition: transform var(--transition-base), box-shadow var(--transition-base);
    border: 2px solid transparent;
}

.theme-card:hover {
    transform: translateY(-5px) scale(1.02);
    box-shadow: var(--shadow-xl);
    border-color: var(--primary);
}

.theme-card-header {
    display: flex;
    align-items: center;
    gap: var(--spacing-md);
    margin-bottom: var(--spacing-md);
}

.theme-icon {
    width: 48px;
    height: 48px;
    display: flex;
    align-items: center;
    justify-content: center;
    border-radius: var(--radius-md);
    font-size: var(--font-size-2xl);
}

.theme-info h3 {
    font-size: var(--font-size-lg);
    font-weight: 700;
    color: var(--text-primary);
}

.theme-count {
    font-size: var(--font-size-sm);
    color: var(--text-secondary);
}

.theme-progress {
    margin-top: var(--spacing-md);
}

.theme-progress-bar {
    height: 6px;
    background: var(--border);
    border-radius: var(--radius-full);
    overflow: hidden;
    margin-bottom: var(--spacing-xs);
}

.theme-progress-fill {
    height: 100%;
    background: linear-gradient(90deg, var(--primary), var(--secondary));
    border-radius: var(--radius-full);
    transition: width 1s ease;
}

.theme-progress-text {
    font-size: var(--font-size-xs);
    color: var(--text-light);
}

.carousel-btn {
    position: absolute;
    top: 50%;
    transform: translateY(-50%);
    width: 48px;
    height: 48px;
    background: var(--white);
    border-radius: 50%;
    box-shadow: var(--shadow-lg);
    display: flex;
    align-items: center;
    justify-content: center;
    z-index: 10;
    transition: all var(--transition-base);
}

.carousel-btn:hover {
    background: var(--primary);
    color: var(--white);
    transform: translateY(-50%) scale(1.1);
}

.carousel-btn.prev {
    left: var(--spacing-md);
}

.carousel-btn.next {
    right: var(--spacing-md);
}

/* ===========================
   How It Works Section
   =========================== */
.how-it-works {
    background: var(--background-light);
}

.steps {
    display: grid;
    gap: var(--spacing-3xl);
}

.step {
    display: grid;
    grid-template-columns: auto 1fr auto;
    gap: var(--spacing-xl);
    align-items: center;
    opacity: 0;
    transform: translateY(30px);
}

.step.visible {
    animation: fadeInUp 0.6s ease forwards;
}

.step:nth-child(even) {
    direction: rtl;
}

.step:nth-child(even) > * {
    direction: ltr;
}

.step-number {
    font-size: var(--font-size-4xl);
    font-weight: 800;
    background: linear-gradient(135deg, var(--primary), var(--secondary));
    -webkit-background-clip: text;
    -webkit-text-fill-color: transparent;
    background-clip: text;
}

.step-content {
    max-width: 400px;
}

.step-title {
    font-size: var(--font-size-2xl);
    font-weight: 700;
    margin-bottom: var(--spacing-sm);
    color: var(--text-primary);
}

.step-description {
    color: var(--text-secondary);
    font-size: var(--font-size-lg);
    line-height: 1.7;
}

.step-visual {
    width: 300px;
    height: 200px;
}

.visual-box {
    width: 100%;
    height: 100%;
    background: var(--white);
    border-radius: var(--radius-xl);
    box-shadow: var(--shadow-lg);
    display: flex;
    align-items: center;
    justify-content: center;
    padding: var(--spacing-lg);
}

.theme-select {
    flex-direction: column;
    gap: var(--spacing-sm);
}

.theme-option {
    width: 100%;
    padding: var(--spacing-md);
    border-radius: var(--radius-md);
    background: var(--background-light);
    text-align: center;
    font-weight: 600;
    transition: all var(--transition-base);
    cursor: pointer;
}

.theme-option.selected {
    background: linear-gradient(135deg, var(--primary), var(--secondary));
    color: var(--white);
    transform: scale(1.05);
}

.difficulty-select {
    display: flex;
    gap: var(--spacing-sm);
}

.diff-btn {
    padding: var(--spacing-sm) var(--spacing-md);
    border-radius: var(--radius-md);
    font-weight: 600;
    border: 2px solid var(--border);
    background: var(--white);
    transition: all var(--transition-base);
    cursor: pointer;
}

.diff-btn.easy { border-color: rgba(26, 255, 136, 0.3); color: #0D8B4D; }
.diff-btn.medium { border-color: rgba(255, 165, 0, 0.3); color: #CC7000; }
.diff-btn.hard { border-color: rgba(255, 68, 88, 0.3); color: #CC1A2F; }

.diff-btn.selected {
    transform: scale(1.1);
}

.diff-btn.easy.selected { background: rgba(26, 255, 136, 0.2); }
.diff-btn.medium.selected { background: rgba(255, 165, 0, 0.2); }
.diff-btn.hard.selected { background: rgba(255, 68, 88, 0.2); }

.swipe-card-visual {
    position: relative;
    width: 100%;
    height: 120px;
    background: linear-gradient(135deg, var(--primary), var(--secondary));
    border-radius: var(--radius-md);
    display: flex;
    align-items: center;
    justify-content: space-between;
    padding: var(--spacing-lg);
    color: var(--white);
}

.swipe-gesture {
    font-size: var(--font-size-3xl);
    font-weight: 700;
    opacity: 0.5;
    animation: gestureFloat 2s ease infinite;
}

.left-gesture {
    color: var(--danger);
    animation-delay: 0s;
}

.right-gesture {
    color: var(--success);
    animation-delay: 1s;
}

@keyframes gestureFloat {
    0%, 100% { opacity: 0.3; transform: scale(1); }
    50% { opacity: 0.8; transform: scale(1.2); }
}

.question-preview {
    flex: 1;
    text-align: center;
    font-weight: 600;
}

.progress-visual {
    position: relative;
}

.progress-circle {
    width: 120px;
    height: 120px;
    position: relative;
}

.progress-circle svg {
    transform: rotate(-90deg);
}

.progress-percent {
    position: absolute;
    top: 50%;
    left: 50%;
    transform: translate(-50%, -50%);
    font-size: var(--font-size-2xl);
    font-weight: 700;
    color: var(--primary);
}

.confetti {
    position: absolute;
    top: -20px;
    left: 50%;
    transform: translateX(-50%);
    width: 10px;
    height: 10px;
    background: var(--success);
    border-radius: 2px;
    animation: confettiFall 3s ease infinite;
}

.confetti::before,
.confetti::after {
    content: '';
    position: absolute;
    width: 10px;
    height: 10px;
    border-radius: 2px;
}

.confetti::before {
    background: var(--primary);
    left: -15px;
    animation: confettiFall 3s ease infinite 0.3s;
}

.confetti::after {
    background: var(--secondary);
    right: -15px;
    animation: confettiFall 3s ease infinite 0.6s;
}

@keyframes confettiFall {
    0% { transform: translateY(0) rotate(0deg); opacity: 1; }
    100% { transform: translateY(150px) rotate(360deg); opacity: 0; }
}

/* ===========================
   Statistics Section
   =========================== */
.stats {
    background: linear-gradient(135deg, var(--primary), var(--secondary));
    color: var(--white);
}

.stats-grid {
    display: grid;
    grid-template-columns: repeat(auto-fit, minmax(250px, 1fr));
    gap: var(--spacing-xl);
}

.stat-card {
    text-align: center;
    padding: var(--spacing-xl);
    background: rgba(255, 255, 255, 0.1);
    backdrop-filter: blur(10px);
    border-radius: var(--radius-xl);
    border: 1px solid rgba(255, 255, 255, 0.2);
    opacity: 0;
    transform: scale(0.8);
}

.stat-card.visible {
    animation: scaleIn 0.6s ease forwards;
}

@keyframes scaleIn {
    to {
        opacity: 1;
        transform: scale(1);
    }
}

.stat-icon {
    font-size: var(--font-size-4xl);
    margin-bottom: var(--spacing-sm);
}

.stat-number {
    font-size: var(--font-size-5xl);
    font-weight: 800;
    display: inline-block;
}

.stat-suffix {
    font-size: var(--font-size-3xl);
    font-weight: 800;
    display: inline-block;
}

.stat-label {
    font-size: var(--font-size-lg);
    opacity: 0.9;
    margin-top: var(--spacing-xs);
}

/* ===========================
   Dark Mode Demo Section
   =========================== */
.dark-mode-demo {
    background: var(--background-light);
}

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

.mode-preview {
    padding: var(--spacing-lg);
}

.preview-label {
    text-align: center;
    font-weight: 700;
    font-size: var(--font-size-lg);
    margin-bottom: var(--spacing-md);
    color: var(--text-primary);
}

.preview-screen {
    border-radius: var(--radius-xl);
    overflow: hidden;
    box-shadow: var(--shadow-xl);
    aspect-ratio: 9/16;
    max-width: 300px;
    margin: 0 auto;
}

.preview-header {
    height: 60px;
    display: flex;
    align-items: center;
    padding: 0 var(--spacing-md);
}

.preview-header.light {
    background: var(--white);
    border-bottom: 1px solid var(--border);
}

.preview-header.dark {
    background: #1F2937;
    border-bottom: 1px solid #374151;
}

.preview-content {
    padding: var(--spacing-md);
    height: calc(100% - 60px);
    display: flex;
    flex-direction: column;
    gap: var(--spacing-md);
}

.preview-content.light {
    background: var(--background-light);
}

.preview-content.dark {
    background: var(--background-dark);
}

.preview-card {
    height: 120px;
    border-radius: var(--radius-md);
}

.preview-card.light {
    background: var(--white);
    box-shadow: var(--shadow-sm);
}

.preview-card.dark {
    background: #1F2937;
    box-shadow: 0 1px 3px rgba(0, 0, 0, 0.5);
}

.mode-toggle {
    display: flex;
    justify-content: center;
}

.theme-toggle {
    width: 80px;
    height: 40px;
    background: var(--white);
    border-radius: var(--radius-full);
    box-shadow: var(--shadow-lg);
    padding: 4px;
    cursor: pointer;
    transition: background var(--transition-base);
}

.theme-toggle:hover {
    box-shadow: var(--shadow-xl);
}

.toggle-track {
    width: 100%;
    height: 100%;
    position: relative;
}

.toggle-thumb {
    position: absolute;
    width: 32px;
    height: 32px;
    background: linear-gradient(135deg, var(--primary), var(--secondary));
    border-radius: 50%;
    display: flex;
    align-items: center;
    justify-content: center;
    color: var(--white);
    transition: transform var(--transition-base);
    left: 0;
}

.theme-toggle.dark .toggle-thumb {
    transform: translateX(40px);
}

.sun-icon,
.moon-icon {
    position: absolute;
    transition: opacity var(--transition-fast);
}

.moon-icon {
    opacity: 0;
}

.theme-toggle.dark .sun-icon {
    opacity: 0;
}

.theme-toggle.dark .moon-icon {
    opacity: 1;
}

/* ===========================
   Tech Stack Section
   =========================== */
.tech-stack {
    background: var(--white);
}

.tech-badges {
    display: flex;
    flex-wrap: wrap;
    justify-content: center;
    gap: var(--spacing-md);
}

.tech-badge {
    padding: var(--spacing-md) var(--spacing-lg);
    background: var(--white);
    border: 2px solid var(--border);
    border-radius: var(--radius-full);
    font-weight: 600;
    font-size: var(--font-size-lg);
    transition: all var(--transition-base);
    opacity: 0;
    transform: translateY(20px);
}

.tech-badge.visible {
    animation: fadeInUp 0.5s ease forwards;
}

.tech-badge:hover {
    border-color: var(--primary);
    color: var(--primary);
    transform: translateY(-5px);
    box-shadow: var(--shadow-md);
}

/* ===========================
   Final CTA Section
   =========================== */
.final-cta {
    background: linear-gradient(135deg, 
        rgba(26, 140, 255, 0.1),
        rgba(136, 25, 255, 0.1));
    padding: var(--spacing-3xl) 0;
}

.cta-content {
    text-align: center;
    max-width: 700px;
    margin: 0 auto;
}

.cta-character {
    margin-bottom: var(--spacing-xl);
}

.character-celebration {
    position: relative;
    display: inline-block;
    animation: celebrationBounce 2s ease infinite;
}

@keyframes celebrationBounce {
    0%, 100% { transform: translateY(0) scale(1); }
    50% { transform: translateY(-20px) scale(1.05); }
}

.celebration-confetti {
    position: absolute;
    top: 0;
    left: 50%;
    transform: translateX(-50%);
    width: 100%;
    height: 100%;
    pointer-events: none;
}

.cta-title {
    font-size: var(--font-size-4xl);
    font-weight: 800;
    margin-bottom: var(--spacing-md);
    color: var(--text-primary);
}

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

/* ===========================
   Footer
   =========================== */
.footer {
    background: var(--text-primary);
    color: var(--white);
    padding: var(--spacing-3xl) 0 var(--spacing-lg);
}

.footer-content {
    display: grid;
    grid-template-columns: 1.5fr 1fr;
    gap: var(--spacing-3xl);
    margin-bottom: var(--spacing-2xl);
}

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

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

.footer-tagline {
    color: rgba(255, 255, 255, 0.7);
    font-size: var(--font-size-lg);
}

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

.footer-column h4 {
    font-size: var(--font-size-lg);
    font-weight: 700;
    margin-bottom: var(--spacing-md);
}

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

.footer-column a {
    color: rgba(255, 255, 255, 0.7);
    transition: color var(--transition-base);
}

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

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

.footer-bottom p:first-child {
    margin-bottom: var(--spacing-xs);
}

/* ===========================
   Responsive Design
   =========================== */
@media (max-width: 1024px) {
    .hero-container {
        grid-template-columns: 1fr;
        gap: var(--spacing-2xl);
    }
    
    .hero-visual {
        order: -1;
    }
    
    .card-stack {
        max-width: 350px;
        height: 450px;
    }
    
    .demo-card {
        height: 350px;
    }
    
    .mode-comparison {
        grid-template-columns: 1fr;
        gap: var(--spacing-2xl);
    }
    
    .mode-toggle {
        order: 2;
    }
    
    .step {
        grid-template-columns: 1fr;
        text-align: center;
    }
    
    .step:nth-child(even) {
        direction: ltr;
    }
    
    .step-visual {
        margin: 0 auto;
    }
}

@media (max-width: 768px) {
    :root {
        --font-size-5xl: 2rem;
        --font-size-4xl: 1.75rem;
        --font-size-3xl: 1.5rem;
        --spacing-3xl: 3rem;
    }
    
    .nav-toggle {
        display: flex;
    }
    
    .nav-links {
        position: absolute;
        top: 70px;
        left: 0;
        right: 0;
        background: var(--white);
        flex-direction: column;
        align-items: stretch;
        padding: var(--spacing-md);
        box-shadow: var(--shadow-lg);
        transform: translateY(-100%);
        opacity: 0;
        pointer-events: none;
        transition: all var(--transition-base);
    }
    
    .nav-links.active {
        transform: translateY(0);
        opacity: 1;
        pointer-events: all;
    }
    
    .nav-links a {
        padding: var(--spacing-md);
        text-align: center;
    }
    
    .nav-cta {
        margin-top: var(--spacing-sm);
    }
    
    .hero {
        min-height: auto;
        padding: calc(70px + var(--spacing-2xl)) 0 var(--spacing-2xl);
    }
    
    .hero-title {
        font-size: var(--font-size-3xl);
    }
    
    .hero-subtitle {
        font-size: var(--font-size-lg);
    }
    
    .hero-cta {
        flex-direction: column;
    }
    
    .hero-cta .btn {
        width: 100%;
    }
    
    .card-stack {
        max-width: 100%;
        height: 400px;
    }
    
    .demo-card {
        height: 300px;
        padding: var(--spacing-lg);
    }
    
    .features-grid {
        grid-template-columns: 1fr;
    }
    
    .carousel-btn {
        display: none;
    }
    
    .stats-grid {
        grid-template-columns: repeat(2, 1fr);
    }
    
    .footer-content {
        grid-template-columns: 1fr;
    }
    
    .footer-links {
        grid-template-columns: 1fr;
    }
}

@media (max-width: 480px) {
    .container {
        padding: 0 var(--spacing-sm);
    }
    
    .section-title {
        font-size: var(--font-size-2xl);
    }
    
    .section-subtitle {
        font-size: var(--font-size-base);
    }
    
    .stats-grid {
        grid-template-columns: 1fr;
    }
    
    .tech-badges {
        gap: var(--spacing-sm);
    }
    
    .tech-badge {
        font-size: var(--font-size-base);
        padding: var(--spacing-sm) var(--spacing-md);
    }
}

/* ===========================
   Accessibility
   =========================== */
.sr-only {
    position: absolute;
    width: 1px;
    height: 1px;
    padding: 0;
    margin: -1px;
    overflow: hidden;
    clip: rect(0, 0, 0, 0);
    white-space: nowrap;
    border-width: 0;
}

:focus-visible {
    outline: 2px solid var(--primary);
    outline-offset: 2px;
}

/* ===========================
   Print Styles
   =========================== */
@media print {
    .nav,
    .hero-visual,
    .feature-visual,
    .carousel-btn,
    .mode-toggle,
    .final-cta,
    .footer {
        display: none;
    }
    
    body {
        color: black;
        background: white;
    }
    
    section {
        page-break-inside: avoid;
    }
}