:root {
  --bg: #f5f6f8; --surface: #fff; --text: #1d2330; --muted: #6b7280; --line: #e3e6eb;
  --primary: #2f5bea; --primary-ink: #fff; --ok: #1f9d55; --warn: #c27c0e; --danger: #d64545;
  --radius: 10px;
}
@media (prefers-color-scheme: dark) {
  :root {
    --bg: #111418; --surface: #1a1f26; --text: #e6e8eb; --muted: #9aa3ae; --line: #2a313b;
    --primary: #5b7cfa; --ok: #3cc47c; --warn: #e3a33a; --danger: #ef6b6b;
  }
}
* { box-sizing: border-box; }
body { margin: 0; background: var(--bg); color: var(--text);
  font: 15px/1.55 -apple-system, "Segoe UI", "Malgun Gothic", "Apple SD Gothic Neo", sans-serif; }
a { color: var(--primary); text-decoration: none; }
a:hover { text-decoration: underline; }
h1 { font-size: 1.5rem; margin: .2em 0 .6em; }
h2 { font-size: 1.15rem; margin: 1.2em 0 .6em; }
h3 { font-size: 1rem; margin: 1em 0 .5em; }
code { background: var(--bg); padding: 1px 5px; border-radius: 4px; font-size: .9em; }
.wrap { max-width: 1100px; margin: 0 auto; padding: 0 16px; }
.main { padding-top: 20px; padding-bottom: 60px; }

.topbar { background: var(--surface); border-bottom: 1px solid var(--line); position: sticky; top: 0; z-index: 10; }
.topbar-in { display: flex; align-items: center; gap: 20px; height: 56px; }
.brand { font-weight: 800; font-size: 1.15rem; color: var(--text); letter-spacing: .02em; }
.nav { display: flex; gap: 16px; flex: 1; }
.nav a { color: var(--text); }
.me { display: flex; align-items: center; gap: 10px; margin-left: auto; }
.me-name { color: var(--text); }

.card { background: var(--surface); border: 1px solid var(--line); border-radius: var(--radius); padding: 18px; margin-bottom: 16px; }
.cards { display: grid; grid-template-columns: repeat(auto-fill, minmax(260px, 1fr)); gap: 14px; margin-bottom: 16px; }
.cards .card { margin: 0; }
.course-card h3 { margin-top: 0; }
a.course-card { color: var(--text); display: block; }
a.course-card:hover { text-decoration: none; border-color: var(--primary); }
.grid2 { display: grid; grid-template-columns: 1fr 1fr; gap: 16px; }
.empty { color: var(--muted); text-align: center; }
.page-head { display: flex; justify-content: space-between; align-items: center; gap: 12px; flex-wrap: wrap; }
.crumb { margin: 0; font-size: .9rem; }

.btn { display: inline-block; border: 1px solid var(--line); background: var(--surface); color: var(--text);
  padding: 8px 14px; border-radius: 8px; cursor: pointer; font: inherit; line-height: 1.2; }
.btn:hover { text-decoration: none; border-color: var(--primary); }
.btn:disabled { opacity: .5; cursor: default; }
.btn-primary { background: var(--primary); border-color: var(--primary); color: var(--primary-ink); }
.btn-danger { color: var(--danger); border-color: var(--danger); }
.btn-ghost { background: transparent; }
.btn-sm { padding: 5px 10px; font-size: .85rem; }
.btn-block { width: 100%; padding: 11px; }

.form { display: flex; flex-direction: column; gap: 12px; }
.form label { display: flex; flex-direction: column; gap: 4px; font-weight: 600; font-size: .9rem; }
.form label.check { flex-direction: row; align-items: center; gap: 8px; font-weight: 400; }
.form-row { flex-direction: row; flex-wrap: wrap; align-items: center; }
.form-row > input, .form-row > select { flex: 1 1 160px; }
input, select, textarea { font: inherit; color: var(--text); background: var(--surface); border: 1px solid var(--line);
  border-radius: 8px; padding: 8px 10px; }
input:focus, select:focus, textarea:focus { outline: 2px solid var(--primary); outline-offset: -1px; }
.inline { display: inline-flex; gap: 6px; align-items: center; margin: 2px 0; }
.filters { display: flex; flex-wrap: wrap; gap: 8px; align-items: center; }

.auth-box { max-width: 440px; margin: 30px auto; }
.center { text-align: center; }
.muted { color: var(--muted); }
.small { font-size: .85rem; }
.warn { color: var(--warn); }
.nowrap { white-space: nowrap; }
.prewrap { white-space: pre-wrap; }
.clamp { display: -webkit-box; -webkit-line-clamp: 3; -webkit-box-orient: vertical; overflow: hidden; }
.spacer { flex: 1; }

.role-pick { border: 0; padding: 0; margin: 0; display: grid; grid-template-columns: 1fr 1fr; gap: 10px; }
.role-pick legend { font-weight: 600; font-size: .9rem; margin-bottom: 6px; }
.role-opt { flex-direction: row !important; align-items: flex-start; gap: 8px !important; border: 1px solid var(--line);
  border-radius: 8px; padding: 10px; cursor: pointer; font-weight: 400 !important; }
.role-opt:has(input:checked) { border-color: var(--primary); background: color-mix(in srgb, var(--primary) 8%, transparent); }
.role-opt small { display: block; color: var(--muted); }

.alert { padding: 10px 14px; border-radius: 8px; margin-bottom: 14px; border: 1px solid var(--line); background: var(--surface); }
.alert ul { margin: 0; padding-left: 18px; }
.alert-ok { border-color: var(--ok); color: var(--ok); }
.alert-error { border-color: var(--danger); color: var(--danger); }
.alert-info { border-color: var(--primary); }

.badge { display: inline-block; font-size: .75rem; padding: 2px 8px; border-radius: 99px; background: var(--bg);
  border: 1px solid var(--line); color: var(--muted); font-weight: 600; vertical-align: middle; }
.badge-ok { color: var(--ok); border-color: var(--ok); }
.badge-warn { color: var(--warn); border-color: var(--warn); }
.badge-admin { color: var(--danger); border-color: var(--danger); }
.badge-instructor { color: var(--primary); border-color: var(--primary); }

.bar { height: 8px; background: var(--bg); border-radius: 99px; overflow: hidden; border: 1px solid var(--line); }
.bar span { display: block; height: 100%; background: var(--primary); transition: width .3s; }

.table-wrap { overflow-x: auto; }
.table { width: 100%; border-collapse: collapse; }
.table th, .table td { padding: 9px 8px; border-bottom: 1px solid var(--line); text-align: left; vertical-align: middle; }
.table th { font-size: .82rem; color: var(--muted); font-weight: 600; }
.row-pending { background: color-mix(in srgb, var(--warn) 7%, transparent); }
.grid-table td.center, .grid-table th { text-align: center; }
.cell-ok { color: var(--ok); font-weight: 700; }
.cell-mid { color: var(--warn); }

.list { list-style: none; padding: 8px 18px; }
.list li { padding: 6px 0; }
.lessons { padding-left: 38px; }
.lessons li { padding: 8px 0; border-bottom: 1px solid var(--line); }
.lessons li:last-child { border-bottom: 0; }
.lessons a { display: flex; gap: 10px; align-items: center; color: var(--text); }
.lessons .lt { flex: 1; }
.kind { font-size: .72rem; padding: 2px 7px; border-radius: 5px; background: var(--bg); color: var(--muted); white-space: nowrap; }
.kind-live { color: var(--danger); }

.lesson-admin { padding-left: 22px; }
.lesson-admin > li { padding: 12px 0; border-bottom: 1px solid var(--line); }
.la-head { display: flex; align-items: center; gap: 8px; flex-wrap: wrap; }
.uploader { margin: 8px 0; display: flex; flex-direction: column; gap: 6px; }
.up-actions { display: flex; gap: 8px; flex-wrap: wrap; align-items: center; }
.err { white-space: pre-wrap; background: var(--bg); padding: 8px; border-radius: 6px; color: var(--danger); max-height: 160px; overflow: auto; }
details.mini summary { cursor: pointer; color: var(--muted); font-size: .85rem; }
details.card summary { cursor: pointer; }
.danger-zone { border-color: var(--danger); }
.dl { display: grid; grid-template-columns: max-content 1fr; gap: 8px 16px; margin: 0; }
.dl dt { color: var(--muted); }
.dl dd { margin: 0; word-break: break-all; }

.player { position: relative; background: #000; border-radius: var(--radius); overflow: hidden; aspect-ratio: 16/9; user-select: none; }
.player video { width: 100%; height: 100%; display: block; background: #000; }
.player:fullscreen { border-radius: 0; aspect-ratio: auto; }
.watermark { position: absolute; pointer-events: none; color: rgba(255,255,255,.28); font-size: 14px; font-weight: 600;
  text-shadow: 0 0 2px rgba(0,0,0,.5); white-space: nowrap; transition: left 1s, top 1s; }
.fs-btn { position: absolute; right: 10px; top: 10px; background: rgba(0,0,0,.45); color: #fff; border: 0; border-radius: 6px;
  width: 34px; height: 34px; font-size: 18px; cursor: pointer; }
.player-meta { display: flex; align-items: center; gap: 10px; margin: 10px 0 16px; flex-wrap: wrap; }
.player-meta .bar { flex: 1 1 200px; }
.pager { display: flex; justify-content: space-between; gap: 10px; margin-top: 16px; }
.toast { position: fixed; left: 50%; bottom: 30px; transform: translateX(-50%); background: #222; color: #fff; padding: 10px 16px;
  border-radius: 8px; opacity: 0; transition: opacity .2s; pointer-events: none; z-index: 50; }
.toast.show { opacity: 1; }

@media (max-width: 720px) {
  .grid2, .role-pick { grid-template-columns: 1fr; }
  .topbar-in { gap: 10px; }
  .nav { gap: 10px; font-size: .9rem; overflow-x: auto; }
  .me-name .badge { display: none; }
}