:root {
    --bg: #fdfdfd;
    --accent: #111111;
    --border: #ececec;
    --text: #333;
}

body { font-family: 'Inter', -apple-system, sans-serif; background: var(--bg); margin: 0; color: var(--text); }
.navbar { padding: 1.5rem; border-bottom: 1px solid var(--border); display: flex; justify-content: space-between; align-items: center; background: #fff; }
.navbar a { text-decoration: none; color: var(--accent); font-weight: 500; }

.login-card { max-width: 400px; margin: 15vh auto; padding: 3rem; background: #fff; border: 1px solid var(--border); border-radius: 12px; text-align: center; box-shadow: 0 10px 25px rgba(0,0,0,0.05); }
input { width: 100%; padding: 12px; margin: 20px 0; border: 1px solid var(--border); border-radius: 6px; box-sizing: border-box; }
.btn { width: 100%; padding: 12px; background: var(--accent); color: #fff; border: none; border-radius: 6px; cursor: pointer; font-weight: 600; }

.dashboard-container { max-width: 1100px; margin: 4rem auto; padding: 0 2rem; }
.grid { display: grid; grid-template-columns: repeat(auto-fit, minmax(300px, 1fr)); gap: 2rem; }
.section-card { background: #fff; border: 1px solid var(--border); border-radius: 12px; padding: 1.5rem; }
.section-card h3 { border-bottom: 1px solid var(--border); padding-bottom: 10px; }

.lesson-link { display: block; padding: 10px; color: #666; text-decoration: none; border-radius: 6px; }
.lesson-link:hover { background: #f5f5f5; color: var(--accent); }

.video-wrapper { position: relative; padding-bottom: 56.25%; height: 0; background: #000; border-radius: 12px; overflow: hidden; margin: 2rem 0; }
.video-wrapper iframe { position: absolute; top: 0; left: 0; width: 100%; height: 100%; }
.video-content { max-width: 900px; margin: 0 auto; padding: 2rem; }
.badge { background: #eee; padding: 4px 12px; border-radius: 20px; font-size: 0.8rem; font-weight: 600; }

@media (max-width: 768px) {
    .grid { grid-template-columns: 1fr; }
}