* { box-sizing: border-box; margin: 0; padding: 0; }
body { font-family: -apple-system, Segoe UI, Roboto, Arial, sans-serif; background: #0f172a; color: #e2e8f0; }

/* ---------- Landing page ---------- */
.landing-header { text-align: center; padding: 30px 20px 10px; }
.landing-header .logo { max-height: 70px; }
.landing-header h1 { font-size: 28px; }

.ad-banner { display: block; text-align: center; margin: 10px auto 20px; max-width: 900px; }
.ad-banner img { max-width: 100%; border-radius: 8px; }

.login-box {
    max-width: 400px; margin: 40px auto; background: #1e293b;
    padding: 30px; border-radius: 12px; text-align: center;
}
.login-box h2 { margin-bottom: 10px; }
.login-box .subtitle { color: #94a3b8; font-size: 14px; margin-bottom: 20px; }
.login-box input {
    width: 100%; padding: 12px; margin-bottom: 12px; border-radius: 6px;
    border: 1px solid #334155; background: #0f172a; color: #fff; font-size: 16px;
    text-align: center; letter-spacing: 1px;
}
.login-box button {
    width: 100%; padding: 12px; border: none; border-radius: 6px;
    background: #6366f1; color: #fff; font-size: 16px; cursor: pointer;
}
.login-box button:hover { background: #4f46e5; }

.alert { padding: 10px; border-radius: 6px; margin-bottom: 15px; font-size: 14px; }
.alert-error { background: #7f1d1d; color: #fecaca; }

.landing-footer { text-align: center; padding: 20px; color: #64748b; font-size: 13px; }

/* ---------- Dashboard ---------- */
.dash-header {
    display: flex; justify-content: space-between; align-items: center;
    padding: 20px 30px; background: #1e293b; flex-wrap: wrap; gap: 10px;
}
.dash-header a { color: #93c5fd; text-decoration: none; }
.user-info { font-size: 14px; color: #cbd5e1; }

.course-desc { padding: 15px 30px; color: #94a3b8; }

.video-list { max-width: 700px; margin: 20px auto; padding: 0 20px; }
.video-item {
    display: flex; align-items: center; gap: 15px;
    background: #1e293b; padding: 15px 20px; margin-bottom: 10px;
    border-radius: 8px; text-decoration: none; color: #e2e8f0;
}
.video-item:hover { background: #273449; }
.video-number {
    background: #6366f1; color: #fff; width: 28px; height: 28px;
    border-radius: 50%; display: flex; align-items: center; justify-content: center;
    font-size: 13px; flex-shrink: 0;
}
.video-title { flex-grow: 1; }
.video-duration { color: #64748b; font-size: 13px; }

/* ---------- Player page ---------- */
.player-page { user-select: none; }
.video-wrapper { position: relative; max-width: 900px; margin: 20px auto; padding: 0 20px; }
.video-wrapper video { width: 100%; border-radius: 8px; background: #000; }

.watermark-overlay {
    position: absolute; top: 20px; right: 30px;
    color: rgba(255,255,255,0.35); font-size: 13px;
    pointer-events: none; text-shadow: 0 0 3px rgba(0,0,0,0.8);
}