/* ===================================
   CSS Variables & Design System
   =================================== */
:root {
    /* Colors */
    --color-primary: #6366f1;
    --color-primary-dark: #4f46e5;
    --color-primary-light: #818cf8;
    --color-secondary: #ec4899;
    --color-accent: #14b8a6;
    
    --color-bg-primary: #0f172a;
    --color-bg-secondary: #1e293b;
    --color-bg-tertiary: #334155;
    
    --color-text-primary: #f8fafc;
    --color-text-secondary: #cbd5e1;
    --color-text-muted: #94a3b8;
    
    --color-border: rgba(148, 163, 184, 0.1);
    --color-border-hover: rgba(148, 163, 184, 0.2);
    
    /* Gradients */
    --gradient-primary: linear-gradient(135deg, #667eea 0%, #764ba2 100%);
    --gradient-secondary: linear-gradient(135deg, #f093fb 0%, #f5576c 100%);
    --gradient-accent: linear-gradient(135deg, #4facfe 0%, #00f2fe 100%);
    --gradient-text: linear-gradient(135deg, #667eea 0%, #ec4899 50%, #14b8a6 100%);
    
    /* 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-primary: 'Inter', -apple-system, BlinkMacSystemFont, sans-serif;
    --font-korean: 'Noto Sans KR', 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;
    
    /* 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 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);
    --shadow-glow: 0 0 30px rgba(99, 102, 241, 0.3);
    
    /* Transitions */
    --transition-fast: 150ms cubic-bezier(0.4, 0, 0.2, 1);
    --transition-base: 300ms cubic-bezier(0.4, 0, 0.2, 1);
    --transition-slow: 500ms cubic-bezier(0.4, 0, 0.2, 1);
}

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

html {
    scroll-behavior: smooth;
    font-size: 16px;
}

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

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

/* ===================================
   Navigation
   =================================== */
.navbar {
    position: fixed;
    top: 0;
    left: 0;
    right: 0;
    z-index: 1000;
    background: rgba(15, 23, 42, 0.8);
    backdrop-filter: blur(12px);
    border-bottom: 1px solid var(--color-border);
    transition: all var(--transition-base);
}

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

.nav-brand {
    font-size: var(--font-size-xl);
    font-weight: 800;
}

.brand-text {
    color: var(--color-text-primary);
}

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

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

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

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

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

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

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

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

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

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

.gradient-orb {
    position: absolute;
    border-radius: 50%;
    filter: blur(80px);
    opacity: 0.3;
    animation: float 20s ease-in-out infinite;
}

.orb-1 {
    width: 500px;
    height: 500px;
    background: var(--gradient-primary);
    top: -250px;
    right: -100px;
    animation-delay: 0s;
}

.orb-2 {
    width: 400px;
    height: 400px;
    background: var(--gradient-secondary);
    bottom: -200px;
    left: -100px;
    animation-delay: 7s;
}

.orb-3 {
    width: 350px;
    height: 350px;
    background: var(--gradient-accent);
    top: 50%;
    left: 50%;
    transform: translate(-50%, -50%);
    animation-delay: 14s;
}

@keyframes float {
    0%, 100% { transform: translate(0, 0) scale(1); }
    33% { transform: translate(30px, -30px) scale(1.1); }
    66% { transform: translate(-20px, 20px) scale(0.9); }
}

.hero-content {
    position: relative;
    z-index: 1;
    text-align: center;
    max-width: 900px;
    margin: 0 auto;
}

.hero-badge {
    display: inline-flex;
    align-items: center;
    gap: var(--spacing-xs);
    padding: var(--spacing-xs) var(--spacing-md);
    background: rgba(99, 102, 241, 0.1);
    border: 1px solid rgba(99, 102, 241, 0.2);
    border-radius: var(--radius-full);
    color: var(--color-primary-light);
    font-size: var(--font-size-sm);
    font-weight: 600;
    margin-bottom: var(--spacing-lg);
    animation: slideDown 0.8s ease-out;
}

.badge-icon {
    font-size: var(--font-size-lg);
}

.hero-title {
    font-size: var(--font-size-5xl);
    font-weight: 900;
    line-height: 1.1;
    margin-bottom: var(--spacing-lg);
    animation: slideUp 0.8s ease-out 0.2s both;
}

.title-line {
    display: block;
}

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

.hero-description {
    font-size: var(--font-size-xl);
    color: var(--color-text-secondary);
    margin-bottom: var(--spacing-xl);
    line-height: 1.8;
    animation: slideUp 0.8s ease-out 0.4s both;
}

.hero-cta {
    display: flex;
    gap: var(--spacing-md);
    justify-content: center;
    margin-bottom: var(--spacing-3xl);
    animation: slideUp 0.8s ease-out 0.6s both;
}

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

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

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

.btn-secondary {
    background: rgba(255, 255, 255, 0.05);
    color: var(--color-text-primary);
    border: 1px solid var(--color-border);
    backdrop-filter: blur(10px);
}

.btn-secondary:hover {
    background: rgba(255, 255, 255, 0.1);
    border-color: var(--color-border-hover);
    transform: translateY(-2px);
}

.hero-stats {
    display: flex;
    align-items: center;
    justify-content: center;
    gap: var(--spacing-xl);
    animation: slideUp 0.8s ease-out 0.8s both;
}

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

.stat-number {
    font-size: var(--font-size-3xl);
    font-weight: 800;
    background: var(--gradient-text);
    -webkit-background-clip: text;
    -webkit-text-fill-color: transparent;
    background-clip: text;
}

.stat-label {
    font-size: var(--font-size-sm);
    color: var(--color-text-muted);
    text-transform: uppercase;
    letter-spacing: 0.05em;
}

.stat-divider {
    width: 1px;
    height: 40px;
    background: var(--color-border);
}

.scroll-indicator {
    position: absolute;
    bottom: var(--spacing-xl);
    left: 50%;
    transform: translateX(-50%);
    animation: bounce 2s ease-in-out infinite;
}

.mouse {
    width: 24px;
    height: 40px;
    border: 2px solid var(--color-text-muted);
    border-radius: var(--radius-full);
    position: relative;
}

.wheel {
    width: 4px;
    height: 8px;
    background: var(--color-text-muted);
    border-radius: var(--radius-full);
    position: absolute;
    top: 8px;
    left: 50%;
    transform: translateX(-50%);
    animation: scroll 1.5s ease-in-out infinite;
}

@keyframes slideDown {
    from {
        opacity: 0;
        transform: translateY(-20px);
    }
    to {
        opacity: 1;
        transform: translateY(0);
    }
}

@keyframes slideUp {
    from {
        opacity: 0;
        transform: translateY(20px);
    }
    to {
        opacity: 1;
        transform: translateY(0);
    }
}

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

@keyframes scroll {
    0% { opacity: 0; transform: translateX(-50%) translateY(0); }
    50% { opacity: 1; }
    100% { opacity: 0; transform: translateX(-50%) translateY(16px); }
}

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

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

.section-badge {
    display: inline-block;
    padding: var(--spacing-xs) var(--spacing-md);
    background: rgba(99, 102, 241, 0.1);
    border: 1px solid rgba(99, 102, 241, 0.2);
    border-radius: var(--radius-full);
    color: var(--color-primary-light);
    font-size: var(--font-size-sm);
    font-weight: 600;
    text-transform: uppercase;
    letter-spacing: 0.05em;
    margin-bottom: var(--spacing-md);
}

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

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

/* ===================================
   Skills Section
   =================================== */
.skills {
    background: var(--color-bg-secondary);
}

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

.skill-category {
    background: rgba(255, 255, 255, 0.02);
    border: 1px solid var(--color-border);
    border-radius: var(--radius-xl);
    padding: var(--spacing-xl);
    transition: all var(--transition-base);
    position: relative;
    overflow: hidden;
}

.skill-category::before {
    content: '';
    position: absolute;
    top: 0;
    left: 0;
    right: 0;
    height: 3px;
    background: var(--gradient-primary);
    transform: scaleX(0);
    transition: transform var(--transition-base);
}

.skill-category:hover {
    transform: translateY(-4px);
    border-color: var(--color-border-hover);
    box-shadow: var(--shadow-xl);
}

.skill-category:hover::before {
    transform: scaleX(1);
}

.category-icon {
    font-size: var(--font-size-3xl);
    margin-bottom: var(--spacing-md);
}

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

.skill-tags {
    display: flex;
    flex-wrap: wrap;
    gap: var(--spacing-xs);
}

.skill-tag {
    padding: var(--spacing-xs) var(--spacing-md);
    background: rgba(99, 102, 241, 0.1);
    border: 1px solid rgba(99, 102, 241, 0.2);
    border-radius: var(--radius-full);
    font-size: var(--font-size-sm);
    color: var(--color-text-secondary);
    transition: all var(--transition-fast);
}

.skill-tag:hover {
    background: rgba(99, 102, 241, 0.2);
    color: var(--color-text-primary);
    transform: translateY(-2px);
}

/* ===================================
   Projects Section
   =================================== */
.projects-grid {
    display: grid;
    grid-template-columns: repeat(auto-fill, minmax(350px, 1fr));
    gap: var(--spacing-xl);
}

.project-card {
    background: rgba(255, 255, 255, 0.02);
    border: 1px solid var(--color-border);
    border-radius: var(--radius-xl);
    overflow: hidden;
    transition: all var(--transition-base);
    cursor: pointer;
    text-decoration: none;
    color: inherit;
    display: block;
}

.project-card:hover {
    transform: translateY(-8px);
    border-color: var(--color-border-hover);
    box-shadow: var(--shadow-2xl);
}

.project-image {
    width: 100%;
    aspect-ratio: 16 / 10;
    object-fit: cover;
    transition: transform var(--transition-slow);
}

.project-card:hover .project-image {
    transform: scale(1.05);
}

.project-info {
    padding: var(--spacing-lg);
}

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

.project-tags {
    display: flex;
    flex-wrap: wrap;
    gap: var(--spacing-xs);
}

.project-tag {
    padding: 4px var(--spacing-sm);
    background: rgba(99, 102, 241, 0.1);
    border: 1px solid rgba(99, 102, 241, 0.2);
    border-radius: var(--radius-sm);
    font-size: var(--font-size-xs);
    color: var(--color-text-muted);
}

/* ===================================
   Contact Section
   =================================== */
.contact {
    background: var(--color-bg-secondary);
}

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

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

.contact-description {
    font-size: var(--font-size-lg);
    color: var(--color-text-secondary);
    margin-bottom: var(--spacing-xl);
    line-height: 1.8;
}

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

.contact-method {
    display: flex;
    align-items: center;
    gap: var(--spacing-md);
    padding: var(--spacing-md);
    background: rgba(255, 255, 255, 0.02);
    border: 1px solid var(--color-border);
    border-radius: var(--radius-lg);
    text-decoration: none;
    color: inherit;
    transition: all var(--transition-base);
}

.contact-method:hover {
    background: rgba(255, 255, 255, 0.05);
    border-color: var(--color-border-hover);
    transform: translateX(8px);
}

.method-icon {
    font-size: var(--font-size-2xl);
    width: 48px;
    height: 48px;
    display: flex;
    align-items: center;
    justify-content: center;
    background: rgba(99, 102, 241, 0.1);
    border-radius: var(--radius-lg);
}

.method-label {
    font-size: var(--font-size-sm);
    color: var(--color-text-muted);
    text-transform: uppercase;
    letter-spacing: 0.05em;
}

.method-value {
    font-size: var(--font-size-base);
    color: var(--color-text-primary);
    font-weight: 500;
}

.contact-visual {
    position: relative;
}

.visual-card {
    background: rgba(255, 255, 255, 0.02);
    border: 1px solid var(--color-border);
    border-radius: var(--radius-2xl);
    padding: var(--spacing-xl);
    position: relative;
    overflow: hidden;
}

.card-glow {
    position: absolute;
    top: -50%;
    left: -50%;
    width: 200%;
    height: 200%;
    background: radial-gradient(circle, rgba(99, 102, 241, 0.1) 0%, transparent 70%);
    animation: rotate 20s linear infinite;
}

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

.card-content {
    position: relative;
    z-index: 1;
}

.availability-badge {
    display: inline-flex;
    align-items: center;
    gap: var(--spacing-xs);
    padding: var(--spacing-sm) var(--spacing-md);
    background: rgba(20, 184, 166, 0.1);
    border: 1px solid rgba(20, 184, 166, 0.2);
    border-radius: var(--radius-full);
    color: var(--color-accent);
    font-size: var(--font-size-sm);
    font-weight: 600;
    margin-bottom: var(--spacing-xl);
}

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

@keyframes pulse {
    0%, 100% { opacity: 1; }
    50% { opacity: 0.5; }
}

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

.contact-stat {
    display: flex;
    align-items: center;
    gap: var(--spacing-md);
}

.stat-icon {
    font-size: var(--font-size-2xl);
    width: 56px;
    height: 56px;
    display: flex;
    align-items: center;
    justify-content: center;
    background: var(--gradient-primary);
    border-radius: var(--radius-lg);
}

.stat-value {
    font-size: var(--font-size-2xl);
    font-weight: 800;
    color: var(--color-text-primary);
}

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

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

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

.footer-text {
    color: var(--color-text-muted);
    font-size: var(--font-size-sm);
    margin-top: var(--spacing-sm);
}

/* ===================================
   Modal
   =================================== */
.modal {
    position: fixed;
    top: 0;
    left: 0;
    right: 0;
    bottom: 0;
    z-index: 2000;
    display: none;
    align-items: center;
    justify-content: center;
    padding: var(--spacing-lg);
}

.modal.active {
    display: flex;
}

.modal-overlay {
    position: absolute;
    top: 0;
    left: 0;
    right: 0;
    bottom: 0;
    background: rgba(0, 0, 0, 0.8);
    backdrop-filter: blur(8px);
}

.modal-content {
    position: relative;
    z-index: 1;
    background: var(--color-bg-secondary);
    border: 1px solid var(--color-border);
    border-radius: var(--radius-xl);
    max-width: 1200px;
    max-height: 90vh;
    overflow-y: auto;
    box-shadow: var(--shadow-2xl);
}

.modal-close {
    position: absolute;
    top: var(--spacing-md);
    right: var(--spacing-md);
    width: 40px;
    height: 40px;
    display: flex;
    align-items: center;
    justify-content: center;
    background: rgba(255, 255, 255, 0.1);
    border: 1px solid var(--color-border);
    border-radius: var(--radius-lg);
    color: var(--color-text-primary);
    cursor: pointer;
    transition: all var(--transition-base);
    z-index: 10;
}

.modal-close:hover {
    background: rgba(255, 255, 255, 0.2);
    transform: rotate(90deg);
}

.modal-body {
    padding: var(--spacing-xl);
}

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

@media (max-width: 768px) {
    :root {
        --font-size-5xl: 2.5rem;
        --font-size-4xl: 2rem;
        --font-size-3xl: 1.75rem;
    }
    
    .nav-menu {
        display: none;
    }
    
    .mobile-menu-toggle {
        display: flex;
    }
    
    .hero-title {
        font-size: var(--font-size-4xl);
    }
    
    .hero-description {
        font-size: var(--font-size-base);
    }
    
    .hero-cta {
        flex-direction: column;
    }
    
    .hero-stats {
        flex-direction: column;
        gap: var(--spacing-lg);
    }
    
    .stat-divider {
        width: 40px;
        height: 1px;
    }
    
    .skills-grid {
        grid-template-columns: 1fr;
    }
    
    .projects-grid {
        grid-template-columns: 1fr;
    }
    
    .contact-title {
        font-size: var(--font-size-3xl);
    }
    
    .section-title {
        font-size: var(--font-size-3xl);
    }
}

@media (max-width: 480px) {
    .container {
        padding: 0 var(--spacing-md);
    }
    
    section {
        padding: var(--spacing-2xl) 0;
    }
    
    .hero {
        padding: var(--spacing-2xl) 0;
    }
}