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

:root {
    --primary-color: #2563eb;
    --primary-dark: #1e40af;
    --primary-light: #3b82f6;
    --secondary-color: #10b981;
    --accent-color: #f59e0b;
    --danger-color: #ef4444;
    --text-primary: #1f2937;
    --text-secondary: #6b7280;
    --text-light: #9ca3af;
    --bg-primary: #ffffff;
    --bg-secondary: #f9fafb;
    --bg-dark: #1f2937;
    --border-color: #e5e7eb;
    --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);
    --transition: all 0.3s ease;
}

html {
    scroll-behavior: smooth;
}

body {
    font-family: 'Noto Sans KR', -apple-system, BlinkMacSystemFont, 'Segoe UI', sans-serif;
    font-size: 16px;
    line-height: 1.8;
    color: var(--text-primary);
    background-color: var(--bg-secondary);
    overflow-x: hidden;
}

/* ================================
   Header Styles
================================ */
.site-header {
    background: linear-gradient(135deg, var(--primary-color) 0%, var(--primary-dark) 100%);
    color: white;
    padding: 0;
    box-shadow: var(--shadow-lg);
    position: sticky;
    top: 0;
    z-index: 1000;
    animation: slideDown 0.5s ease-out;
}

@keyframes slideDown {
    from {
        transform: translateY(-100%);
        opacity: 0;
    }
    to {
        transform: translateY(0);
        opacity: 1;
    }
}

.header-container {
    max-width: 1200px;
    margin: 0 auto;
    padding: 1rem 2rem;
    display: flex;
    justify-content: space-between;
    align-items: center;
}

.logo a {
    text-decoration: none;
    color: white;
    display: block;
}

.logo h1 {
    font-size: 1.8rem;
    font-weight: 900;
    margin-bottom: 0.25rem;
    letter-spacing: -0.5px;
    text-shadow: 2px 2px 4px rgba(0, 0, 0, 0.2);
}

.logo-subtitle {
    font-size: 0.875rem;
    font-weight: 300;
    opacity: 0.95;
    letter-spacing: 0.5px;
}

.mobile-menu-toggle {
    display: none;
    flex-direction: column;
    background: transparent;
    border: none;
    cursor: pointer;
    padding: 0.5rem;
}

.mobile-menu-toggle span {
    width: 25px;
    height: 3px;
    background: white;
    margin: 3px 0;
    transition: var(--transition);
    border-radius: 3px;
}

.main-nav ul {
    list-style: none;
    display: flex;
    gap: 0.5rem;
}

.main-nav li a {
    color: white;
    text-decoration: none;
    padding: 0.75rem 1.25rem;
    display: block;
    border-radius: 8px;
    font-weight: 500;
    transition: var(--transition);
    position: relative;
    overflow: hidden;
}

.main-nav li a::before {
    content: '';
    position: absolute;
    top: 0;
    left: -100%;
    width: 100%;
    height: 100%;
    background: rgba(255, 255, 255, 0.1);
    transition: var(--transition);
}

.main-nav li a:hover::before,
.main-nav li.active a::before {
    left: 0;
}

.main-nav li a:hover {
    background: rgba(255, 255, 255, 0.15);
    transform: translateY(-2px);
}

.main-nav li.active a {
    background: rgba(255, 255, 255, 0.2);
    font-weight: 700;
}

/* ================================
   Main Content Styles
================================ */
.main-content {
    min-height: calc(100vh - 400px);
    padding: 3rem 0;
}

.container {
    max-width: 1200px;
    margin: 0 auto;
    padding: 0 2rem;
}

/* Hero Section */
.hero-section {
    background: linear-gradient(135deg, var(--primary-color) 0%, var(--primary-dark) 100%);
    color: white;
    padding: 5rem 2rem;
    text-align: center;
    position: relative;
    overflow: hidden;
}

.hero-section::before {
    content: '';
    position: absolute;
    top: 0;
    left: 0;
    right: 0;
    bottom: 0;
    background: url('data:image/svg+xml,<svg xmlns="http://www.w3.org/2000/svg" viewBox="0 0 1440 320"><path fill="rgba(255,255,255,0.1)" d="M0,96L48,112C96,128,192,160,288,160C384,160,480,128,576,122.7C672,117,768,139,864,149.3C960,160,1056,160,1152,138.7C1248,117,1344,75,1392,53.3L1440,32L1440,320L1392,320C1344,320,1248,320,1152,320C1056,320,960,320,864,320C768,320,672,320,576,320C480,320,384,320,288,320C192,320,96,320,48,320L0,320Z"></path></svg>') no-repeat bottom;
    background-size: cover;
    opacity: 0.3;
}

.hero-content {
    position: relative;
    z-index: 1;
    max-width: 800px;
    margin: 0 auto;
}

.hero-section h1 {
    font-size: 3rem;
    font-weight: 900;
    margin-bottom: 1.5rem;
    line-height: 1.2;
    text-shadow: 2px 2px 4px rgba(0, 0, 0, 0.2);
    animation: fadeInUp 0.8s ease-out;
}

.hero-section .subtitle {
    font-size: 1.35rem;
    margin-bottom: 2rem;
    opacity: 0.95;
    font-weight: 400;
    line-height: 1.6;
    animation: fadeInUp 0.8s ease-out 0.2s both;
}

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

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

/* Content Section */
.content-section {
    background: white;
    border-radius: 16px;
    padding: 3rem;
    margin: 2rem auto;
    box-shadow: var(--shadow-lg);
    animation: fadeIn 0.6s ease-out;
}

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

.content-section h2 {
    font-size: 2rem;
    color: var(--primary-color);
    margin-bottom: 1.5rem;
    padding-bottom: 1rem;
    border-bottom: 3px solid var(--primary-color);
    font-weight: 700;
    position: relative;
}

.content-section h2::after {
    content: '';
    position: absolute;
    bottom: -3px;
    left: 0;
    width: 60px;
    height: 3px;
    background: var(--accent-color);
}

.content-section h3 {
    font-size: 1.5rem;
    color: var(--text-primary);
    margin: 2rem 0 1rem;
    font-weight: 600;
    padding-left: 1rem;
    border-left: 4px solid var(--secondary-color);
}

.content-section h4 {
    font-size: 1.25rem;
    color: var(--text-primary);
    margin: 1.5rem 0 1rem;
    font-weight: 600;
}

.content-section p {
    margin-bottom: 1.25rem;
    line-height: 1.9;
    color: var(--text-secondary);
}

.content-section ul,
.content-section ol {
    margin: 1.5rem 0;
    padding-left: 2rem;
}

.content-section li {
    margin-bottom: 0.75rem;
    line-height: 1.8;
    color: var(--text-secondary);
}

/* Info Cards */
.info-cards {
    display: grid;
    grid-template-columns: repeat(auto-fit, minmax(300px, 1fr));
    gap: 2rem;
    margin: 2rem 0;
}

.info-card {
    background: linear-gradient(135deg, #ffffff 0%, #f8fafc 100%);
    border-radius: 16px;
    padding: 2rem;
    box-shadow: var(--shadow-md);
    transition: var(--transition);
    border: 2px solid transparent;
    position: relative;
    overflow: hidden;
}

.info-card::before {
    content: '';
    position: absolute;
    top: 0;
    left: 0;
    width: 100%;
    height: 4px;
    background: linear-gradient(90deg, var(--primary-color), var(--secondary-color));
}

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

.info-card h3 {
    color: var(--primary-color);
    margin: 0 0 1rem 0;
    font-size: 1.5rem;
    border: none;
    padding: 0;
    font-weight: 700;
}

.info-card .icon {
    font-size: 3rem;
    margin-bottom: 1rem;
    display: block;
}

/* Highlight Box */
.highlight-box {
    background: linear-gradient(135deg, #eff6ff 0%, #dbeafe 100%);
    border-left: 5px solid var(--primary-color);
    border-radius: 12px;
    padding: 2rem;
    margin: 2rem 0;
    box-shadow: var(--shadow-sm);
    position: relative;
    overflow: hidden;
}

.highlight-box::before {
    content: '💡';
    position: absolute;
    top: 1rem;
    right: 1rem;
    font-size: 3rem;
    opacity: 0.15;
}

.highlight-box.warning {
    background: linear-gradient(135deg, #fef3c7 0%, #fde68a 100%);
    border-left-color: var(--accent-color);
}

.highlight-box.warning::before {
    content: '⚠️';
}

.highlight-box.danger {
    background: linear-gradient(135deg, #fee2e2 0%, #fecaca 100%);
    border-left-color: var(--danger-color);
}

.highlight-box.danger::before {
    content: '⛔';
}

.highlight-box.success {
    background: linear-gradient(135deg, #d1fae5 0%, #a7f3d0 100%);
    border-left-color: var(--secondary-color);
}

.highlight-box.success::before {
    content: '✅';
}

/* Table Styles */
.comparison-table {
    width: 100%;
    border-collapse: collapse;
    margin: 2rem 0;
    background: white;
    border-radius: 12px;
    overflow: hidden;
    box-shadow: var(--shadow-md);
}

.comparison-table thead {
    background: linear-gradient(135deg, var(--primary-color) 0%, var(--primary-dark) 100%);
    color: white;
}

.comparison-table th {
    padding: 1.25rem;
    text-align: left;
    font-weight: 600;
    font-size: 1.1rem;
}

.comparison-table td {
    padding: 1.25rem;
    border-bottom: 1px solid var(--border-color);
}

.comparison-table tbody tr {
    transition: var(--transition);
}

.comparison-table tbody tr:hover {
    background: var(--bg-secondary);
}

.comparison-table tbody tr:last-child td {
    border-bottom: none;
}

/* Button Styles */
.btn {
    display: inline-block;
    padding: 1rem 2rem;
    border-radius: 12px;
    text-decoration: none;
    font-weight: 600;
    transition: var(--transition);
    border: none;
    cursor: pointer;
    font-size: 1rem;
    text-align: center;
    position: relative;
    overflow: hidden;
}

.btn::before {
    content: '';
    position: absolute;
    top: 50%;
    left: 50%;
    width: 0;
    height: 0;
    border-radius: 50%;
    background: rgba(255, 255, 255, 0.3);
    transform: translate(-50%, -50%);
    transition: width 0.6s, height 0.6s;
}

.btn:hover::before {
    width: 300px;
    height: 300px;
}

.btn-primary {
    background: linear-gradient(135deg, var(--primary-color) 0%, var(--primary-dark) 100%);
    color: white;
    box-shadow: var(--shadow-md);
}

.btn-primary:hover {
    transform: translateY(-3px);
    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;
    transform: translateY(-3px);
}

/* TOC (Table of Contents) */
.toc {
    background: var(--bg-secondary);
    border-radius: 12px;
    padding: 2rem;
    margin: 2rem 0;
    border: 2px solid var(--border-color);
}

.toc h3 {
    color: var(--primary-color);
    margin: 0 0 1.5rem 0;
    padding: 0;
    border: none;
    font-size: 1.5rem;
}

.toc ul {
    list-style: none;
    padding: 0;
    margin: 0;
}

.toc li {
    margin: 0.75rem 0;
}

.toc a {
    color: var(--text-primary);
    text-decoration: none;
    transition: var(--transition);
    display: inline-block;
    padding: 0.5rem 0;
}

.toc a:hover {
    color: var(--primary-color);
    transform: translateX(8px);
}

/* ================================
   Footer Styles
================================ */
.site-footer {
    background: linear-gradient(135deg, var(--bg-dark) 0%, #111827 100%);
    color: white;
    padding: 3rem 0 1rem;
    margin-top: 4rem;
}

.footer-container {
    max-width: 1200px;
    margin: 0 auto;
    padding: 0 2rem;
}

.footer-content {
    display: grid;
    grid-template-columns: repeat(auto-fit, minmax(250px, 1fr));
    gap: 3rem;
    margin-bottom: 3rem;
}

.footer-section h3 {
    font-size: 1.5rem;
    margin-bottom: 1rem;
    font-weight: 700;
    color: white;
}

.footer-section h4 {
    font-size: 1.2rem;
    margin-bottom: 1rem;
    font-weight: 600;
    color: var(--primary-light);
}

.footer-section p {
    line-height: 1.8;
    opacity: 0.9;
    margin-bottom: 0.75rem;
}

.footer-description {
    font-size: 0.95rem;
    margin-top: 1rem;
}

.footer-links {
    list-style: none;
    padding: 0;
    margin: 0;
}

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

.footer-links a {
    color: rgba(255, 255, 255, 0.8);
    text-decoration: none;
    transition: var(--transition);
    display: inline-block;
}

.footer-links a:hover {
    color: var(--primary-light);
    transform: translateX(5px);
}

.legal-notice {
    font-size: 0.875rem;
    line-height: 1.7;
    opacity: 0.8;
}

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

.footer-bottom p {
    margin: 0.5rem 0;
    opacity: 0.8;
    font-size: 0.9rem;
}

/* Quick Contact Button */
.quick-contact {
    position: fixed;
    bottom: 2rem;
    right: 2rem;
    z-index: 999;
}

.quick-btn {
    width: 60px;
    height: 60px;
    border-radius: 50%;
    background: linear-gradient(135deg, var(--primary-color) 0%, var(--primary-dark) 100%);
    color: white;
    border: none;
    cursor: pointer;
    box-shadow: var(--shadow-xl);
    transition: var(--transition);
    display: flex;
    align-items: center;
    justify-content: center;
}

.quick-btn:hover {
    transform: translateY(-5px) scale(1.1);
    box-shadow: 0 25px 35px -5px rgba(0, 0, 0, 0.2);
}

/* ================================
   Responsive Design
================================ */
@media (max-width: 768px) {
    .header-container {
        flex-wrap: wrap;
        padding: 1rem;
    }
    
    .mobile-menu-toggle {
        display: flex;
        order: 3;
    }
    
    .logo {
        order: 1;
    }
    
    .logo h1 {
        font-size: 1.3rem;
    }
    
    .logo-subtitle {
        font-size: 0.75rem;
    }
    
    .main-nav {
        order: 4;
        width: 100%;
        max-height: 0;
        overflow: hidden;
        transition: max-height 0.3s ease;
    }
    
    .main-nav.active {
        max-height: 500px;
    }
    
    .main-nav ul {
        flex-direction: column;
        padding: 1rem 0;
        gap: 0;
    }
    
    .main-nav li a {
        padding: 1rem;
        border-radius: 0;
    }
    
    .hero-section {
        padding: 3rem 1.5rem;
    }
    
    .hero-section h1 {
        font-size: 2rem;
    }
    
    .hero-section .subtitle {
        font-size: 1.1rem;
    }
    
    .content-section {
        padding: 2rem 1.5rem;
        margin: 1rem;
    }
    
    .content-section h2 {
        font-size: 1.5rem;
    }
    
    .content-section h3 {
        font-size: 1.25rem;
    }
    
    .info-cards {
        grid-template-columns: 1fr;
        gap: 1.5rem;
    }
    
    .container {
        padding: 0 1rem;
    }
    
    .comparison-table {
        font-size: 0.9rem;
    }
    
    .comparison-table th,
    .comparison-table td {
        padding: 0.75rem;
    }
    
    .footer-content {
        grid-template-columns: 1fr;
        gap: 2rem;
    }
    
    .quick-btn {
        width: 50px;
        height: 50px;
    }
    
    .quick-contact {
        bottom: 1.5rem;
        right: 1.5rem;
    }
}

@media (max-width: 480px) {
    .hero-section h1 {
        font-size: 1.75rem;
    }
    
    .cta-buttons {
        flex-direction: column;
    }
    
    .btn {
        width: 100%;
    }
}

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

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

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

.mt-1 { margin-top: 0.5rem; }
.mt-2 { margin-top: 1rem; }
.mt-3 { margin-top: 1.5rem; }
.mt-4 { margin-top: 2rem; }

.mb-1 { margin-bottom: 0.5rem; }
.mb-2 { margin-bottom: 1rem; }
.mb-3 { margin-bottom: 1.5rem; }
.mb-4 { margin-bottom: 2rem; }

.font-bold { font-weight: 700; }
.font-semibold { font-weight: 600; }

/* Animations */
@keyframes pulse {
    0%, 100% {
        opacity: 1;
    }
    50% {
        opacity: 0.7;
    }
}

.animate-pulse {
    animation: pulse 2s cubic-bezier(0.4, 0, 0.6, 1) infinite;
}