:root {
    --primary: #2563eb;
    --primary-dark: #1e40af;
    --secondary: #fbbf24;
    --bg-light: #f8fafc;
    --sidebar-bg: #0f172a;
    --text-dark: #1e293b;
    --text-muted: #64748b;
    --white: #ffffff;
}

* {
    margin: 0;
    padding: 0;
    box-sizing: border-box;
    font-family: 'Plus Jakarta Sans', sans-serif;
}

body {
    background-color: var(--bg-light);
    color: var(--text-dark);
    line-height: 1.6;
}

/* Header */
header {
    background: linear-gradient(135deg, var(--primary-dark), var(--primary));
    color: var(--white);
    padding: 4rem 1rem;
    text-align: center;
    clip-path: polygon(0 0, 100% 0, 100% 90%, 0% 100%);
    margin-bottom: -30px;
}

.header-content h1 {
    font-size: 2.8rem;
    font-weight: 700;
    margin-bottom: 0.5rem;
}

/* Layout */
.container {
    display: flex;
    max-width: 1200px;
    margin: 0 auto 50px auto;
    gap: 30px;
    padding: 0 20px;
    position: relative;
    z-index: 10;
}

/* Sidebar */
nav {
    width: 320px;
    background: var(--sidebar-bg);
    border-radius: 20px;
    padding: 30px 15px;
    height: fit-content;
    position: sticky;
    top: 20px;
    box-shadow: 0 20px 25px -5px rgba(0,0,0,0.1);
}

nav .nav-header h3 {
    color: var(--secondary);
    font-size: 0.8rem;
    text-transform: uppercase;
    letter-spacing: 2px;
    margin-bottom: 25px;
    padding-left: 15px;
}

nav ul { list-style: none; }

nav ul li a {
    color: #94a3b8;
    text-decoration: none;
    display: block;
    padding: 14px 18px;
    border-radius: 12px;
    margin-bottom: 8px;
    font-weight: 500;
    transition: all 0.3s ease;
}

nav ul li a:hover {
    background: rgba(255,255,255,0.05);
    color: var(--white);
}

nav ul li a.active {
    background: var(--primary);
    color: var(--white);
    box-shadow: 0 10px 15px -3px rgba(37, 99, 235, 0.4);
}

/* Main Content */
main {
    flex: 1;
    background: var(--white);
    padding: 50px;
    border-radius: 24px;
    box-shadow: 0 4px 6px -1px rgba(0,0,0,0.05);
}

.materi-section {
    display: none;
    animation: fadeIn 0.4s ease-out;
}

.materi-section.active { display: block; }

h2 {
    font-size: 2rem;
    color: var(--sidebar-bg);
    margin-bottom: 20px;
}

.card {
    background: #f1f5f9;
    padding: 25px;
    border-radius: 16px;
    margin: 20px 0;
    border-left: 6px solid var(--secondary);
}

.hero-card {
    background: #eff6ff;
    padding: 30px;
    border-radius: 20px;
    border: 1px solid #bfdbfe;
}

.info-grid {
    display: grid;
    grid-template-columns: repeat(auto-fit, minmax(200px, 1fr));
    gap: 15px;
    margin-top: 20px;
}

.info-item {
    background: var(--white);
    padding: 10px 15px;
    border-radius: 10px;
    font-size: 0.9rem;
}

/* Code */
pre {
    background: #1e293b;
    color: #e2e8f0;
    padding: 25px;
    border-radius: 16px;
    overflow-x: auto;
    font-family: 'Fira Code', monospace;
    font-size: 0.9rem;
    margin: 20px 0;
    line-height: 1.5;
}

footer {
    background: var(--sidebar-bg);
    color: #64748b;
    text-align: center;
    padding: 50px 20px;
}

/* Responsive */
@media (max-width: 992px) {
    .container { flex-direction: column; }
    nav { width: 100%; position: relative; top: 0; }
    header { clip-path: none; padding: 2.5rem 1rem; }
    main { padding: 30px; }
}

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