:root {
    --primary: #2563eb;
    --dark: #1e293b;
    --light: #f8fafc;
    --text: #334155;
}

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

body { background: var(--light); color: var(--text); line-height: 1.6; }
a { text-decoration: none; color: inherit; }
.container { max-width: 1200px; margin: 0 auto; padding: 20px; }
img { max-width: 100%; height: auto; border-radius: 8px; }

/* Navbar */
nav { background: var(--dark); color: white; padding: 15px 0; }
nav .container { display: flex; justify-content: space-between; align-items: center; }
nav ul { display: flex; list-style: none; gap: 20px; }
nav a:hover { color: var(--primary); }

/* Hero */
.hero { text-align: center; padding: 80px 20px; background: white; border-bottom: 1px solid #ddd; }
.hero h1 { font-size: 3rem; color: var(--primary); margin-bottom: 10px; }
.hero h3 { color: #64748b; font-weight: 400; font-style: italic; min-height: 30px; }

/* Grid System */
.grid { display: grid; grid-template-columns: repeat(auto-fit, minmax(300px, 1fr)); gap: 30px; margin-top: 40px; }

/* Cards */
.card { background: white; padding: 20px; border-radius: 12px; box-shadow: 0 4px 6px -1px rgba(0,0,0,0.1); transition: 0.3s; }
.card:hover { transform: translateY(-5px); }
.card h2 { font-size: 1.4rem; margin: 15px 0 10px; }
.btn { display: inline-block; background: var(--primary); color: white; padding: 10px 20px; border-radius: 5px; margin-top: 10px; }

/* Forms */
input, textarea, select { width: 100%; padding: 10px; margin: 10px 0; border: 1px solid #ccc; border-radius: 5px; }
button { cursor: pointer; background: var(--dark); color: white; border: none; padding: 10px 20px; border-radius: 5px; }

/* Course Detail */
.accordion { margin-top: 20px; }
.accordion-item { border: 1px solid #ddd; margin-bottom: 10px; border-radius: 5px; overflow: hidden; }
.accordion-header { background: #e2e8f0; padding: 15px; cursor: pointer; font-weight: bold; }
.accordion-body { padding: 15px; display: none; background: white; }
.accordion-body ul { list-style: none; padding-left: 10px; }
.accordion-body li { padding: 8px 0; border-bottom: 1px solid #eee; }
.video-responsive { overflow:hidden; padding-bottom:56.25%; position:relative; height:0; }
.video-responsive iframe { left:0; top:0; height:100%; width:100%; position:absolute; }

/* Responsive */
@media(max-width: 768px) {
    nav .container { flex-direction: column; gap: 10px; }
    nav ul { flex-wrap: wrap; justify-content: center; }
}