:root {
    --primary-color: #1a237e; /* Deep Indigo */
    --accent-color: #ffc107; /* Amber */
    --text-dark: #263238; /* Slate Dark */
    --text-light: #eceff1; /* Slate Light */
    --bg-light: #f5f5f5;
    --bg-dark: #121212;
    --card-bg-light: #ffffff;
    --card-bg-dark: #1e1e1e;
    --shadow-soft: 0 4px 6px rgba(0, 0, 0, 0.1);
    --shadow-deep: 0 10px 30px rgba(0, 0, 0, 0.2);
    --transition-fast: 0.3s ease;
}

[data-theme="dark"] {
    --bg-light: var(--bg-dark);
    --text-dark: var(--text-light);
    --card-bg-light: var(--card-bg-dark);
    --shadow-soft: 0 4px 6px rgba(0, 0, 0, 0.5);
}

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

body {
    font-family: 'Pretendard', -apple-system, BlinkMacSystemFont, "Segoe UI", Roboto, sans-serif;
    line-height: 1.6;
    color: var(--text-dark);
    background-color: var(--bg-light);
    transition: background-color var(--transition-fast), color var(--transition-fast);
}

.container {
    max-width: 1200px;
    margin: 0 auto;
    padding: 0 20px;
}

/* Header & Navigation */
header {
    background: var(--primary-color);
    color: white;
    padding: 1rem 0;
    position: sticky;
    top: 0;
    z-index: 1000;
    box-shadow: var(--shadow-soft);
}

.navbar {
    display: flex;
    justify-content: space-between;
    align-items: center;
    max-width: 1200px;
    margin: 0 auto;
    padding: 0 20px;
}

.logo {
    font-size: 1.5rem;
    font-weight: 800;
    letter-spacing: 1px;
}

.nav-links {
    list-style: none;
    display: flex;
    gap: 20px;
}

.nav-links a {
    color: white;
    text-decoration: none;
    font-weight: 600;
    transition: color var(--transition-fast);
}

.nav-links a:hover {
    color: var(--accent-color);
}

.icon-btn {
    background: none;
    border: none;
    color: white;
    font-size: 1.2rem;
    cursor: pointer;
}

/* Hero Section */
.hero {
    height: 50vh;
    background: linear-gradient(135deg, var(--primary-color), #303f9f);
    color: white;
    display: flex;
    align-items: center;
    justify-content: center;
    text-align: center;
}

.hero h1 {
    font-size: 4rem;
    margin-bottom: 0.5rem;
    text-shadow: 2px 2px 4px rgba(0, 0, 0, 0.5);
}

.hero p {
    font-size: 1.5rem;
    margin-bottom: 2rem;
    opacity: 0.9;
}

.btn-primary {
    background: var(--accent-color);
    color: var(--text-dark);
    padding: 12px 30px;
    text-decoration: none;
    border-radius: 50px;
    font-weight: bold;
    font-size: 1.1rem;
    transition: transform var(--transition-fast), box-shadow var(--transition-fast);
    display: inline-block;
}

.btn-primary:hover {
    transform: translateY(-3px);
    box-shadow: 0 5px 15px rgba(255, 193, 7, 0.4);
}

/* Sections */
.section {
    padding: 80px 0;
}

.section-title {
    text-align: center;
    font-size: 2.5rem;
    margin-bottom: 40px;
    position: relative;
    padding-bottom: 10px;
}

.section-title::after {
    content: '';
    position: absolute;
    bottom: 0;
    left: 50%;
    transform: translateX(-50%);
    width: 60px;
    height: 4px;
    background: var(--accent-color);
    border-radius: 2px;
}

.subtitle {
    text-align: center;
    font-size: 1.1rem;
    margin-bottom: 40px;
    color: #666;
}

.bg-alt {
    background-color: rgba(26, 35, 126, 0.03);
}

/* Content Layouts */
.content-grid {
    display: grid;
    grid-template-columns: 2fr 1fr;
    gap: 40px;
    align-items: start;
}

.info-card {
    background: var(--card-bg-light);
    padding: 30px;
    border-radius: 15px;
    box-shadow: var(--shadow-deep);
}

.info-card h3 {
    margin-bottom: 20px;
    border-bottom: 2px solid var(--accent-color);
    padding-bottom: 10px;
}

.info-card ul {
    list-style: none;
}

.info-card li {
    margin-bottom: 15px;
    display: flex;
    align-items: center;
    gap: 15px;
    font-size: 1.1rem;
}

.info-card i {
    color: var(--primary-color);
    font-size: 1.2rem;
}

/* Vocations / Tabs */
.tabs {
    display: flex;
    justify-content: center;
    gap: 20px;
    margin-bottom: 40px;
}

.tab-btn {
    padding: 10px 25px;
    border: 2px solid var(--primary-color);
    background: transparent;
    color: var(--primary-color);
    font-weight: bold;
    border-radius: 5px;
    cursor: pointer;
    transition: all var(--transition-fast);
}

.tab-btn.active {
    background: var(--primary-color);
    color: white;
}

.class-grid {
    display: grid;
    grid-template-columns: repeat(auto-fit, minmax(250px, 1fr));
    gap: 25px;
}

.class-card {
    background: var(--card-bg-light);
    padding: 30px;
    border-radius: 12px;
    text-align: center;
    box-shadow: var(--shadow-soft);
    transition: transform var(--transition-fast);
}

.class-card:hover {
    transform: translateY(-5px);
}

.class-card i {
    font-size: 2.5rem;
    color: var(--primary-color);
    margin-bottom: 20px;
}

/* Mechanics / Fragments */
.mechanic-info {
    display: grid;
    grid-template-columns: repeat(auto-fit, minmax(300px, 1fr));
    gap: 30px;
}

.mechanic-card {
    text-align: center;
    padding: 40px 20px;
}

.icon-circle {
    width: 100px;
    height: 100px;
    background: var(--primary-color);
    color: white;
    border-radius: 50%;
    display: flex;
    align-items: center;
    justify-content: center;
    font-size: 2.5rem;
    margin: 0 auto 20px;
    box-shadow: 0 0 0 10px rgba(26, 35, 126, 0.1);
}

/* Footer & Citations */
footer {
    background: #1a237e;
    color: white;
    padding: 60px 0 20px;
    text-align: center;
}

footer h3 {
    margin-bottom: 30px;
    font-size: 1.8rem;
}

.citation-links {
    list-style: none;
    display: flex;
    flex-wrap: wrap;
    justify-content: center;
    gap: 30px;
    margin-bottom: 40px;
}

.citation-links a {
    color: var(--accent-color);
    text-decoration: none;
    font-weight: 500;
}

.citation-links a:hover {
    text-decoration: underline;
}

.copyright {
    opacity: 0.6;
    font-size: 0.9rem;
    border-top: 1px solid rgba(255, 255, 255, 0.1);
    padding-top: 20px;
}

/* Mobile Responsive */
@media (max-width: 768px) {
    .hero h1 {
        font-size: 2.5rem;
    }
    
    .content-grid {
        grid-template-columns: 1fr;
    }
    
    .nav-links {
        display: none;
    }
}