:root {
    --primary: #003366;
    /* TNI AU Blue */
    --accent: #FFCC00;
    /* Gold */
    --light: #f4f4f4;
    --dark: #333;
}

* {
    margin: 0;
    padding: 0;
    box-sizing: border-box;
    font-family: 'Segoe UI', Tahoma, Geneva, Verdana, sans-serif;
}

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

/* Navbar */
nav {
    background: var(--primary);
    padding: 1rem;
    position: sticky;
    top: 0;
    z-index: 1000;
    text-align: center;
}

nav a {
    color: white;
    text-decoration: none;
    margin: 0 15px;
    font-weight: bold;
}

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

/* Hero Section */
.hero {
    background: linear-gradient(rgba(0, 51, 102, 0.9), rgba(0, 51, 102, 0.8)), url('https://source.unsplash.com/1600x900/?airforce,military');
    background-size: cover;
    color: white;
    text-align: center;
    padding: 180px 20px;
}

.hero h1 {
    font-size: 2.5rem;
    margin-bottom: 10px;
    text-transform: uppercase;
    letter-spacing: 2px;
}

.hero p {
    font-size: 1.2rem;
    margin-bottom: 20px;
    max-width: 800px;
    margin-left: auto;
    margin-right: auto;
}

.btn {
    display: inline-block;
    background: var(--accent);
    color: var(--primary);
    padding: 10px 25px;
    text-decoration: none;
    font-weight: bold;
    border-radius: 5px;
    margin-top: 20px;
    border: none;
    cursor: pointer;
}

.btn:hover {
    background: #e6b800;
}

/* Sections */
section {
    padding: 60px 20px;
    max-width: 1000px;
    margin: auto;
}

h2 {
    color: var(--primary);
    text-align: center;
    margin-bottom: 30px;
    border-bottom: 3px solid var(--accent);
    display: inline-block;
    padding-bottom: 5px;
}

.section-title-container {
    text-align: center;
    margin-bottom: 40px;
}

/* Timeline */
.timeline-item {
    background: white;
    padding: 15px;
    margin-bottom: 10px;
    border-left: 5px solid var(--primary);
    box-shadow: 0 2px 5px rgba(0, 0, 0, 0.1);
}

.time {
    font-weight: bold;
    color: var(--primary);
}

/* Form */
.form-box {
    background: white;
    padding: 30px;
    border-radius: 10px;
    box-shadow: 0 4px 10px rgba(0, 0, 0, 0.1);
    max-width: 600px;
    margin: auto;
}

.form-group {
    margin-bottom: 15px;
}

.form-group label {
    display: block;
    margin-bottom: 5px;
    font-weight: bold;
}

.form-group input {
    width: 100%;
    padding: 10px;
    border: 1px solid #ccc;
    border-radius: 5px;
}

.alert {
    padding: 15px;
    margin-bottom: 20px;
    border-radius: 5px;
    text-align: center;
}

.alert-success {
    background: #d4edda;
    color: #155724;
}

.alert-danger {
    background: #f8d7da;
    color: #721c24;
}

/* Materials */
.locked-content {
    text-align: center;
    background: #e9ecef;
    padding: 40px;
    border-radius: 10px;
}

.material-list {
    list-style: none;
}

.material-list li {
    background: white;
    padding: 15px;
    margin-bottom: 10px;
    border-radius: 5px;
    display: flex;
    justify-content: space-between;
    align-items: center;
    box-shadow: 0 2px 5px rgba(0, 0, 0, 0.1);
}

/* Footer */
footer {
    background: var(--primary);
    color: white;
    text-align: center;
    padding: 20px;
    margin-top: 50px;
}

/* Responsive */
@media (max-width: 768px) {
    .hero h1 {
        font-size: 1.8rem;
    }

    nav a {
        display: block;
        margin: 10px 0;
    }
}