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

:root {
    /* Colors */
    --primary: #4F8EF7;
    --primary-dark: #3A6DB5;
    --primary-light: #6BA3FA;
    --secondary: #7C3AED;
    --background: #0A0B0D;
    --surface: #1A1B1F;
    --surface-light: #2A2B2F;
    --text-primary: #FFFFFF;
    --text-secondary: #A0A0A0;
    --text-tertiary: #707070;
    --border: #2A2B2F;
    --success: #22C55E;
    --warning: #F59E0B;
    --error: #EF4444;
    
    /* Gradients */
    --gradient-primary: linear-gradient(135deg, #4F8EF7 0%, #7C3AED 100%);
    --gradient-secondary: linear-gradient(135deg, #667eea 0%, #764ba2 100%);
    
    /* Shadows */
    --shadow-sm: 0 2px 4px rgba(0, 0, 0, 0.3);
    --shadow-md: 0 4px 16px rgba(0, 0, 0, 0.3);
    --shadow-lg: 0 8px 32px rgba(0, 0, 0, 0.4);
    
    /* 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;
    
    /* Transitions */
    --transition-fast: 150ms ease;
    --transition-base: 300ms ease;
    --transition-slow: 500ms ease;
}

html {
    scroll-behavior: smooth;
}

body {
    font-family: 'Pretendard', -apple-system, BlinkMacSystemFont, system-ui, Roboto, sans-serif;
    font-size: 16px;
    line-height: 1.6;
    color: var(--text-primary);
    background-color: var(--background);
    overflow-x: hidden;
}

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

a {
    text-decoration: none;
    color: inherit;
    transition: color var(--transition-base);
}

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

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


/* ========================================
   Header & Navigation
======================================== */
.header {
    position: fixed;
    top: 0;
    left: 0;
    right: 0;
    background: rgba(10, 11, 13, 0.8);
    backdrop-filter: blur(20px);
    -webkit-backdrop-filter: blur(20px);
    border-bottom: 1px solid var(--border);
    z-index: 900;
    transition: all var(--transition-base);
}

.nav {
    display: flex;
    align-items: center;
    justify-content: space-between;
    height: 80px;
}

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

.logo-text {
    font-size: 1.5rem;
    font-weight: 700;
    letter-spacing: -0.02em;
}

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

.nav-link {
    font-weight: 500;
    color: var(--text-secondary);
    transition: color var(--transition-base);
}

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

.nav-lang {
    margin-left: var(--spacing-sm);
}

.lang-icon {
    width: 20px;
    height: 20px;
    margin-right: var(--spacing-xs);
    vertical-align: middle;
}

.nav-lang .nav-link {
    display: flex;
    align-items: center;
    gap: var(--spacing-xs);
}

.nav-toggle {
    display: none;
    flex-direction: column;
    gap: 4px;
    background: none;
    border: none;
    cursor: pointer;
    padding: var(--spacing-xs);
}

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

/* ========================================
   Hero Section
======================================== */
.hero {
    padding-top: 160px;
    padding-bottom: var(--spacing-2xl);
    min-height: 100vh;
    display: flex;
    align-items: center;
    background: radial-gradient(ellipse at top, rgba(79, 142, 247, 0.1) 0%, transparent 50%);
}

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

.hero-title {
    font-size: clamp(2.5rem, 5vw, 4rem);
    font-weight: 800;
    line-height: 1.2;
    letter-spacing: -0.02em;
    margin-bottom: var(--spacing-md);
}

.hero-description {
    font-size: clamp(1.1rem, 2vw, 1.25rem);
    color: var(--text-secondary);
    margin-bottom: var(--spacing-xl);
    max-width: 600px;
    margin-left: auto;
    margin-right: auto;
}

.hero-cta {
    display: flex;
    gap: var(--spacing-md);
    justify-content: center;
    flex-wrap: wrap;
    margin-bottom: var(--spacing-2xl);
}

.btn {
    display: inline-flex;
    align-items: center;
    gap: var(--spacing-xs);
    padding: var(--spacing-sm) var(--spacing-lg);
    border-radius: var(--radius-md);
    font-weight: 600;
    font-size: 1rem;
    transition: all var(--transition-base);
    cursor: pointer;
    border: none;
}

.btn-primary {
    background: var(--gradient-primary);
    color: var(--text-primary);
    box-shadow: 0 4px 16px rgba(79, 142, 247, 0.3);
}

.btn-primary:hover {
    transform: translateY(-2px);
    box-shadow: 0 8px 24px rgba(79, 142, 247, 0.4);
}

.btn-secondary {
    background: var(--surface);
    color: var(--text-primary);
    border: 1px solid var(--border);
}

.btn-secondary:hover {
    background: var(--surface-light);
}

.btn-icon {
    width: 20px;
    height: 20px;
}

.hero-image {
    position: relative;
    max-width: 300px;
    margin: 0 auto;
}

.hero-screenshot {
    border-radius: var(--radius-xl);
    box-shadow: var(--shadow-lg);
}

/* ========================================
   Features Section
======================================== */
.features {
    padding: var(--spacing-2xl) 0;
    background: var(--surface);
}

.section-title {
    font-size: clamp(2rem, 4vw, 3rem);
    font-weight: 700;
    text-align: center;
    margin-bottom: var(--spacing-sm);
    letter-spacing: -0.02em;
}

.section-description {
    font-size: 1.125rem;
    color: var(--text-secondary);
    text-align: center;
    margin-bottom: var(--spacing-2xl);
    max-width: 600px;
    margin-left: auto;
    margin-right: auto;
}

.features-grid {
    display: grid;
    grid-template-columns: repeat(2, 1fr);
    gap: var(--spacing-lg);
    max-width: 1000px;
    margin: 0 auto;
}

.feature-card {
    background: var(--background);
    border: 1px solid var(--border);
    border-radius: var(--radius-lg);
    padding: var(--spacing-lg);
    transition: all var(--transition-base);
}

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

.feature-icon {
    width: 48px;
    height: 48px;
    margin-bottom: var(--spacing-md);
    color: var(--primary);
}

.feature-title {
    font-size: 1.25rem;
    font-weight: 600;
    margin-bottom: var(--spacing-sm);
}

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

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

.feature-list li {
    padding-left: 1.5rem;
    position: relative;
    margin-bottom: var(--spacing-xs);
    color: var(--text-secondary);
    font-size: 0.875rem;
}

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

/* ========================================
   Screenshots Section
======================================== */
.screenshots {
    padding: var(--spacing-2xl) 0;
    background: var(--background);
}

.screenshots-carousel {
    position: relative;
    max-width: 320px;
    margin: 0 auto;
}

.screenshot-container {
    position: relative;
    aspect-ratio: 9/19.5;
    overflow: hidden;
    border-radius: var(--radius-xl);
    box-shadow: var(--shadow-lg);
    background: var(--surface);
    padding: var(--spacing-md);
}

.screenshot {
    position: absolute;
    top: var(--spacing-md);
    left: var(--spacing-md);
    width: calc(100% - var(--spacing-lg));
    height: calc(100% - var(--spacing-lg));
    opacity: 0;
    transition: opacity var(--transition-slow);
    object-fit: cover;
    border-radius: var(--radius-md);
}

.screenshot.active {
    opacity: 1;
}

.screenshot-dots {
    display: flex;
    justify-content: center;
    gap: var(--spacing-xs);
    margin-top: var(--spacing-lg);
}

.dot {
    width: 8px;
    height: 8px;
    border-radius: 50%;
    background: var(--surface-light);
    border: none;
    cursor: pointer;
    transition: all var(--transition-base);
}

.dot.active {
    width: 24px;
    border-radius: 4px;
    background: var(--primary);
}

/* ========================================
   Download Section
======================================== */
.download {
    padding: var(--spacing-2xl) 0;
    background: var(--surface);
}

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

.download-buttons {
    margin-top: var(--spacing-xl);
}

.download-btn {
    display: inline-block;
    transition: transform var(--transition-base);
}

.download-btn:hover {
    transform: scale(1.05);
}

.download-badge {
    height: 60px;
    width: auto;
}

.download-note {
    margin-top: var(--spacing-md);
    color: var(--text-tertiary);
    font-size: 0.875rem;
}

/* ========================================
   Footer
======================================== */
.footer {
    padding: var(--spacing-xl) 0;
    background: var(--background);
    border-top: 1px solid var(--border);
}

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

.footer-brand {
    margin-bottom: var(--spacing-lg);
}

.footer-logo {
    font-size: 1.5rem;
    font-weight: 700;
    margin-bottom: var(--spacing-xs);
}

.footer-tagline {
    color: var(--text-secondary);
    font-size: 0.875rem;
}

.footer-links {
    display: flex;
    gap: var(--spacing-lg);
    justify-content: center;
    margin-bottom: var(--spacing-lg);
}

.footer-link {
    color: var(--text-secondary);
    font-size: 0.875rem;
}

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

.footer-contact {
    margin-bottom: var(--spacing-md);
    color: var(--text-secondary);
    font-size: 0.875rem;
}

.footer-email {
    color: var(--primary);
    text-decoration: none;
}

.footer-email:hover {
    text-decoration: underline;
}

.footer-copyright {
    color: var(--text-tertiary);
    font-size: 0.875rem;
}

/* ========================================
   Responsive Design
======================================== */
@media (max-width: 1024px) {
    .features-grid {
        grid-template-columns: 1fr;
    }
}

@media (max-width: 768px) {
    .nav-menu {
        position: fixed;
        left: -100%;
        top: 80px;
        flex-direction: column;
        background-color: var(--surface);
        width: 100%;
        text-align: center;
        transition: 0.3s;
        box-shadow: 0 10px 40px rgba(0, 0, 0, 0.3);
        padding: var(--spacing-lg) 0;
        border-top: 1px solid var(--border);
        z-index: 800;
    }
    
    .nav-menu li {
        display: flex;
        justify-content: center;
        align-items: center;
    }
    
    .nav-lang {
        margin-left: 0;
    }
    
    .nav-lang .nav-link {
        justify-content: center;
    }
    
    .nav-menu.active {
        left: 0;
    }
    
    .nav-toggle {
        display: flex;
    }
    
    .nav-toggle.active span:nth-child(2) {
        opacity: 0;
    }
    
    .nav-toggle.active span:nth-child(1) {
        transform: translateY(6px) rotate(45deg);
    }
    
    .nav-toggle.active span:nth-child(3) {
        transform: translateY(-6px) rotate(-45deg);
    }
    
    .hero-cta {
        flex-direction: column;
        align-items: center;
    }
    
    .btn {
        width: 100%;
        max-width: 300px;
        justify-content: center;
    }
    
    .features-grid {
        grid-template-columns: 1fr;
    }
    
    .hero-image {
        max-width: 250px;
    }
    
    .screenshots-carousel {
        max-width: 280px;
    }
    
    .footer-links {
        flex-direction: column;
        gap: var(--spacing-sm);
    }
}

@media (max-width: 480px) {
    .hero {
        padding-top: 120px;
    }
    
    .hero-title {
        font-size: 2rem;
    }
    
    .hero-description {
        font-size: 1rem;
    }
    
    .section-title {
        font-size: 1.75rem;
    }
}