:root {
    --bg-primary: #0b0f19;
    --bg-secondary: #131b2e;
    --bg-tertiary: #1e293b;
    --accent: #4f46e5;
    --accent-hover: #6366f1;
    --accent-glow: rgba(79, 70, 229, 0.15);
    --text-primary: #f8fafc;
    --text-secondary: #94a3b8;
    --text-muted: #64748b;
    --border-color: rgba(255, 255, 255, 0.08);
    --success: #10b981;
    --card-shadow: 0 10px 30px -10px rgba(0, 0, 0, 0.5);
    --transition: all 0.3s cubic-bezier(0.4, 0, 0.2, 1);
    --font-heading: 'NanumGothic', sans-serif;
    --font-body: 'NanumGothic', sans-serif;
}

code, pre, kbd, samp, .tool-output, textarea, #url-input {
    font-family: 'Cascadia Mono', monospace;
}

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

body {
    background-color: var(--bg-primary);
    color: var(--text-primary);
    font-family: var(--font-body);
    line-height: 1.6;
    overflow-x: hidden;
}

h1, h2, h3, h4, h5, h6 {
    font-family: var(--font-heading);
    font-weight: 700;
    letter-spacing: -0.02em;
}

/* Header & Navigation */
header {
    background: rgba(19, 27, 46, 0.8);
    backdrop-filter: blur(12px);
    -webkit-backdrop-filter: blur(12px);
    border-bottom: 1px solid var(--border-color);
    position: sticky;
    top: 0;
    z-index: 100;
    padding: 1rem 2rem;
}

.nav-container {
    max-width: 1200px;
    margin: 0 auto;
    width: 100%;
}

.logo {
    font-family: var(--font-heading);
    font-size: 1.5rem;
    font-weight: 800;
    color: var(--text-primary);
    text-decoration: none;
    background: linear-gradient(135deg, #a78bfa 0%, #6366f1 100%);
    -webkit-background-clip: text;
    -webkit-text-fill-color: transparent;
}

.nav-menu {
    list-style: none;
    gap: 2rem;
}

.nav-link {
    color: var(--text-secondary);
    text-decoration: none;
    font-weight: 500;
    font-size: 0.95rem;
    transition: var(--transition);
    cursor: pointer;
    position: relative;
    padding: 0.25rem 0;
}

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

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

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

/* Hero Section */
.hero {
    padding: 6rem 2rem 4rem;
    text-align: center;
    background: radial-gradient(circle at top, rgba(99, 102, 241, 0.08) 0%, transparent 60%);
}

.hero h1 {
    font-size: 3.5rem;
    margin-bottom: 1.5rem;
    line-height: 1.2;
}

.hero p {
    font-size: 1.2rem;
    color: var(--text-secondary);
    max-width: 600px;
    margin: 0 auto 2rem;
}

.cta-btn {
    display: inline-block;
    padding: 0.8rem 2rem;
    background-color: var(--accent);
    color: var(--text-primary);
    text-decoration: none;
    border-radius: 8px;
    font-weight: 600;
    transition: var(--transition);
    border: none;
    cursor: pointer;
}

.cta-btn:hover {
    background-color: var(--accent-hover);
    transform: translateY(-2px);
    box-shadow: 0 10px 20px -10px rgba(99, 102, 241, 0.5);
}

/* Main Layout */
.main-content {
    max-width: 1200px;
    margin: 0 auto;
    padding: 2rem;
    min-height: 70vh;
}

.page-section {
    display: none;
}

.page-section.active {
    display: block;
    animation: fadeIn 0.5s ease;
}

@keyframes fadeIn {
    from { opacity: 0; transform: translateY(10px); }
    to { opacity: 1; transform: translateY(0); }
}

/* Grid layout for Articles and Tools */
.grid {
    display: grid;
    grid-template-columns: repeat(auto-fit, minmax(320px, 1fr));
    gap: 2rem;
    margin-top: 2rem;
}

.card {
    background-color: var(--bg-secondary);
    border: 1px solid var(--border-color);
    border-radius: 12px;
    padding: 2rem;
    transition: var(--transition);
}

.card:hover {
    transform: translateY(-4px);
    border-color: rgba(99, 102, 241, 0.3);
    box-shadow: var(--card-shadow);
}

.card h3 {
    margin-bottom: 0.75rem;
    font-size: 1.3rem;
}

.card p {
    color: var(--text-secondary);
    font-size: 0.95rem;
    margin-bottom: 1.5rem;
}

.card-link {
    color: var(--accent-hover);
    text-decoration: none;
    font-weight: 600;
    font-size: 0.9rem;
    display: flex;
    align-items: center;
    gap: 0.5rem;
}

/* Tool Interactive Styles */
.tool-box {
    background-color: var(--bg-secondary);
    border: 1px solid var(--border-color);
    border-radius: 16px;
    padding: 2.5rem;
    max-width: 800px;
    margin: 2rem auto;
}

textarea, input[type="text"], input[type="email"] {
    width: 100%;
    background-color: var(--bg-tertiary);
    border: 1px solid var(--border-color);
    border-radius: 8px;
    color: var(--text-primary);
    padding: 1rem;
    font-family: var(--font-body);
    font-size: 1rem;
    margin-bottom: 1rem;
    outline: none;
    transition: var(--transition);
}

textarea:focus, input[type="text"]:focus, input[type="email"]:focus {
    border-color: var(--accent);
    box-shadow: 0 0 0 3px var(--accent-glow);
}

.tool-output {
    background-color: var(--bg-tertiary);
    border-radius: 8px;
    padding: 1rem;
    min-height: 80px;
    border: 1px solid var(--border-color);
    margin-top: 1rem;
    word-break: break-all;
}

/* Article Page / Reader Styles */
.article-full {
    max-width: 800px;
    margin: 0 auto;
    padding-top: 2rem;
}

.article-meta {
    color: var(--text-muted);
    font-size: 0.9rem;
    margin-bottom: 1.5rem;
    display: flex;
    gap: 1rem;
}

.article-content {
    font-size: 1.1rem;
    color: #e2e8f0;
}

.article-content p {
    margin-bottom: 1.5rem;
}

.article-content h2 {
    margin: 2.5rem 0 1rem;
    font-size: 1.75rem;
}

/* Legal Pages (Privacy Policy, Terms) */
.legal-content {
    max-width: 800px;
    margin: 0 auto;
    padding: 2rem 0;
}

.legal-content h2 {
    font-size: 1.6rem;
    margin-top: 2rem;
    margin-bottom: 0.75rem;
}

.legal-content p {
    color: var(--text-secondary);
    margin-bottom: 1rem;
}

.legal-content ul {
    margin-left: 1.5rem;
    margin-bottom: 1rem;
    color: var(--text-secondary);
}

/* Footer */
footer {
    border-top: 1px solid var(--border-color);
    padding: 3rem 2rem;
    margin-top: 5rem;
    background-color: rgba(19, 27, 46, 0.4);
}

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

.footer-links {
    gap: 1.5rem;
    margin-bottom: 1.5rem;
}

.footer-link {
    color: var(--text-muted);
    text-decoration: none;
    font-size: 0.9rem;
    transition: var(--transition);
}

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

.copyright {
    color: var(--text-muted);
    font-size: 0.85rem;
}

/* Responsive utilities */
@media (max-width: 768px) {
    .nav-menu {
        gap: 1rem;
    }
    .hero h1 {
        font-size: 2.2rem;
    }
    .hero p {
        font-size: 1rem;
    }
    .main-content {
        padding: 1rem;
    }
    .card {
        padding: 1.5rem;
    }
}