:root {
  --navy: #1b2b4b;
  --maroon: #7a1d21;
  --bg: #f4f6fa;
  --white: #fff;
  --muted: #5c6578;
  --ok: #1a7f4b;
  --err: #a11;
  --radius: 12px;
  --font: "Segoe UI", system-ui, sans-serif;
}
* { box-sizing: border-box; }
body { margin: 0; font-family: var(--font); background: var(--bg); color: #1a2233; }
a { color: var(--maroon); }
.wrap { width: min(1100px, 94vw); margin: 0 auto; }
.topbar { background: var(--navy); color: #fff; }
.topbar .wrap { display: flex; justify-content: space-between; align-items: center; gap: 1rem; padding: .85rem 0; flex-wrap: wrap; }
.brand { color: #fff; font-weight: 800; text-decoration: none; }
.topbar nav { display: flex; flex-wrap: wrap; gap: .65rem; }
.topbar nav a { color: rgba(255,255,255,.9); text-decoration: none; font-size: .9rem; }
.topbar nav a:hover { color: #fff; }
main.wrap { padding: 1.5rem 0 3rem; }
.foot { padding: 1rem 0 2rem; color: var(--muted); font-size: .85rem; }
h1,h2,h3 { color: var(--navy); }
.muted { color: var(--muted); }
.small { font-size: .85rem; }
.grid { display: grid; gap: 1rem; grid-template-columns: repeat(auto-fit, minmax(180px, 1fr)); }
.card { background: var(--white); border-radius: var(--radius); padding: 1.25rem; box-shadow: 0 8px 24px rgba(18,29,51,.06); }
.stat strong { display: block; font-size: 1.75rem; color: var(--navy); }
.btn, button.btn, input[type=submit] {
  display: inline-block; background: var(--maroon); color: #fff; border: 0; border-radius: 999px;
  padding: .55rem 1.1rem; font-weight: 600; cursor: pointer; text-decoration: none;
}
.btn-secondary { background: var(--navy); }
.btn-ghost { background: transparent; color: var(--navy); border: 1px solid var(--navy); }
.stack { display: flex; flex-direction: column; gap: .75rem; max-width: 520px; }
label { display: flex; flex-direction: column; gap: .3rem; font-weight: 600; font-size: .9rem; }
input, select, textarea {
  font: inherit; padding: .55rem .7rem; border: 1px solid #cfd5e0; border-radius: 8px; font-weight: 400;
}
table { width: 100%; border-collapse: collapse; background: #fff; border-radius: var(--radius); overflow: hidden; }
th, td { padding: .65rem .75rem; border-bottom: 1px solid #e8ecf3; text-align: left; font-size: .92rem; vertical-align: top; }
th { background: var(--navy); color: #fff; }
.flash { padding: .75rem 1rem; border-radius: 8px; margin-bottom: 1rem; }
.flash-success { background: #e7f7ee; color: var(--ok); }
.flash-error { background: #fde8e8; color: var(--err); }
.guest { min-height: 100vh; display: grid; place-items: center; background: linear-gradient(135deg, #121d33, #1b2b4b); }
.login-card { background: #fff; padding: 2rem; border-radius: 16px; width: min(400px, 92vw); }
.split { display: grid; gap: 1.5rem; grid-template-columns: 1fr 1fr; }
@media (max-width: 800px) { .split { grid-template-columns: 1fr; } }
.badge { display: inline-block; padding: .15rem .5rem; border-radius: 999px; font-size: .75rem; font-weight: 700; }
.badge-locked { background: #eee; color: #666; }
.badge-available { background: #e7f0ff; color: #1b2b4b; }
.badge-completed { background: #e7f7ee; color: var(--ok); }
.topic-list { list-style: none; padding: 0; margin: 0; }
.topic-list li { background: #fff; margin-bottom: .5rem; padding: .85rem 1rem; border-radius: 10px; display: flex; justify-content: space-between; gap: 1rem; align-items: center; }
.actions { display: flex; flex-wrap: wrap; gap: .4rem; }
.two-col { display: grid; gap: 1.5rem; grid-template-columns: 1.1fr .9fr; }
@media (max-width: 900px) { .two-col { grid-template-columns: 1fr; } }
img.thumb { max-width: 120px; border-radius: 8px; }
.video-wrap { aspect-ratio: 16/9; background: #000; border-radius: 10px; overflow: hidden; margin: 1rem 0; }
.video-wrap iframe { width: 100%; height: 100%; border: 0; }