:root {
  --bg: #0b0d10;
  --panel: #12161b;
  --panel-2: #171d24;
  --text: #edf2f7;
  --muted: #9aa7b4;
  --accent: #38bdf8;
  --accent-2: #22c55e;
  --border: #26303a;
  --danger: #f87171;
}

* { box-sizing: border-box; }

body {
  margin: 0;
  background: var(--bg);
  color: var(--text);
  font-family: Inter, ui-sans-serif, system-ui, -apple-system, BlinkMacSystemFont, "Segoe UI", sans-serif;
  line-height: 1.55;
}

a { color: var(--accent); text-decoration: none; }
a:hover { text-decoration: underline; }

.topbar {
  position: sticky;
  top: 0;
  z-index: 10;
  display: flex;
  align-items: center;
  gap: 18px;
  padding: 14px 28px;
  background: rgba(11, 13, 16, .92);
  border-bottom: 1px solid var(--border);
  backdrop-filter: blur(12px);
}

.brand { color: var(--text); font-weight: 800; font-size: 20px; letter-spacing: -.02em; }
.brand:hover { text-decoration: none; color: var(--accent); }

.search { display: flex; gap: 8px; flex: 1; max-width: 520px; }
.search input {
  flex: 1;
  min-width: 0;
  background: var(--panel);
  border: 1px solid var(--border);
  color: var(--text);
  border-radius: 10px;
  padding: 9px 12px;
}
.search button, .button, button {
  background: var(--accent);
  color: #06121b;
  border: 0;
  border-radius: 10px;
  padding: 9px 14px;
  font-weight: 700;
  cursor: pointer;
}
.search button:hover, .button:hover, button:hover { filter: brightness(1.08); text-decoration: none; }

.topbar nav { display: flex; align-items: center; gap: 14px; margin-left: auto; }
.topbar nav a { color: var(--muted); }
.topbar nav a:hover { color: var(--text); text-decoration: none; }
.user { color: var(--text); font-weight: 600; }

main { width: min(1180px, calc(100% - 40px)); margin: 0 auto; padding: 34px 0 60px; }
footer { border-top: 1px solid var(--border); color: var(--muted); text-align: center; padding: 22px; font-size: 14px; }

.hero { padding: 42px 0 28px; }
.eyebrow { color: var(--accent); text-transform: uppercase; letter-spacing: .12em; font-weight: 800; font-size: 12px; margin: 0 0 8px; }
h1 { font-size: clamp(34px, 5vw, 58px); line-height: 1.05; letter-spacing: -.04em; margin: 0 0 12px; }
h2 { font-size: 24px; letter-spacing: -.02em; }
h3 { color: var(--muted); text-transform: uppercase; letter-spacing: .08em; font-size: 12px; }

.course-grid { display: grid; grid-template-columns: repeat(auto-fit, minmax(280px, 1fr)); gap: 18px; margin-top: 26px; }
.course-card {
  display: block;
  background: var(--panel);
  border: 1px solid var(--border);
  border-radius: 18px;
  padding: 22px;
  color: var(--text);
  min-height: 210px;
  transition: transform .18s ease, border-color .18s ease;
}
.course-card:hover { transform: translateY(-3px); border-color: var(--accent); text-decoration: none; }
.course-number { color: var(--accent); font-weight: 800; }
.course-card p { color: var(--muted); }
.meta { color: var(--text); font-weight: 700; }

.breadcrumbs { color: var(--muted); margin-bottom: 18px; }
.course-head { max-width: 780px; }
.pill { display: inline-block; border: 1px solid var(--border); border-radius: 999px; padding: 5px 10px; color: var(--muted); font-size: 13px; margin-top: 10px; }

.module { margin-top: 28px; background: var(--panel); border: 1px solid var(--border); border-radius: 18px; padding: 22px; }
.lesson-list { margin: 0; padding-left: 22px; }
.lesson-list li { margin: 8px 0; }

.lesson-layout { display: grid; grid-template-columns: minmax(0, 1fr) 320px; gap: 22px; align-items: start; }
.lesson-main { background: var(--panel); border: 1px solid var(--border); border-radius: 18px; padding: 22px; }
.lesson-description { white-space: pre-wrap; color: #cbd5e1; }
.video-shell { background: #000; border-radius: 14px; overflow: hidden; margin: 18px 0 10px; }
.video-shell iframe { display: block; width: 100%; aspect-ratio: 16 / 9; border: 0; background: #000; }
.pdf-shell { background: var(--panel-2); border: 1px solid var(--border); border-radius: 14px; overflow: hidden; margin: 18px 0; }
.pdf-shell iframe { display: block; width: 100%; height: 70vh; min-height: 420px; border: 0; background: #fff; }
video { display: block; width: 100%; aspect-ratio: 16 / 9; background: #000; }
.stream-note { color: var(--accent-2); font-size: 14px; }
.complete-row { margin-top: 16px; }
.complete-row button.is-complete { background: var(--accent-2); color: #06130a; }

.lesson-side { display: grid; gap: 16px; }
.resources, .lesson-nav { background: var(--panel); border: 1px solid var(--border); border-radius: 18px; padding: 18px; }
.resources ul { list-style: none; padding: 0; margin: 0; }
.resources li { padding: 7px 0; border-bottom: 1px solid var(--border); }
.resources li:last-child { border-bottom: 0; }
.lesson-nav { display: grid; gap: 8px; }

.auth-card { max-width: 420px; margin: 60px auto; background: var(--panel); border: 1px solid var(--border); border-radius: 18px; padding: 28px; }
.auth-card form { display: grid; gap: 14px; }
.auth-card label { display: grid; gap: 6px; color: var(--muted); font-weight: 600; }
.auth-card input { background: var(--bg); border: 1px solid var(--border); border-radius: 10px; color: var(--text); padding: 11px 12px; }
.error { color: var(--danger); }
.success { color: var(--accent-2); }

.stat-grid { display: grid; grid-template-columns: repeat(auto-fit, minmax(160px, 1fr)); gap: 14px; margin: 20px 0; }
.stat-grid div { background: var(--panel); border: 1px solid var(--border); border-radius: 16px; padding: 18px; }
.stat-grid strong { display: block; font-size: 30px; }
.stat-grid span { color: var(--muted); }
.admin-panel { display: grid; grid-template-columns: minmax(0, 1fr) minmax(320px, 520px); gap: 24px; align-items: start; background: var(--panel); border: 1px solid var(--border); border-radius: 18px; padding: 22px; margin: 20px 0; }
.admin-panel-compact { grid-template-columns: minmax(0, 1fr) auto; align-items: center; }
.admin-panel h2 { margin-top: 0; }
.admin-form { display: grid; gap: 14px; }
.admin-form label { display: grid; gap: 6px; color: var(--muted); font-weight: 600; }
.admin-form input { background: var(--bg); border: 1px solid var(--border); border-radius: 10px; color: var(--text); padding: 11px 12px; }
.admin-form button { justify-self: start; }
.button-secondary { background: var(--panel-2); color: var(--text); border: 1px solid var(--border); }
.button-danger { background: rgba(248, 113, 113, .14); color: #fecaca; border: 1px solid rgba(248, 113, 113, .45); }
.table-wrap { width: 100%; overflow-x: auto; border-radius: 16px; }
.action-cell { display: flex; gap: 8px; align-items: center; flex-wrap: wrap; }
.action-cell form { margin: 0; }
.action-cell button { padding: 6px 10px; font-size: 13px; }
table { width: 100%; border-collapse: collapse; background: var(--panel); border: 1px solid var(--border); border-radius: 16px; overflow: hidden; }
th, td { text-align: left; padding: 12px; border-bottom: 1px solid var(--border); }
th { color: var(--muted); text-transform: uppercase; font-size: 12px; letter-spacing: .08em; }

.post-form form { display: grid; gap: 12px; max-width: 720px; }
textarea, select { background: var(--bg); border: 1px solid var(--border); border-radius: 12px; color: var(--text); padding: 12px; width: 100%; }
.posts { display: grid; gap: 14px; margin-top: 22px; }
.post { background: var(--panel); border: 1px solid var(--border); border-radius: 16px; padding: 18px; }
.post header { display: flex; justify-content: space-between; color: var(--muted); margin-bottom: 8px; }

.chat-shell { display: grid; grid-template-columns: 220px minmax(0, 1fr); gap: 18px; align-items: start; }
.chat-side { background: var(--panel); border: 1px solid var(--border); border-radius: 16px; padding: 18px; }
.chat-side ul { list-style: none; padding: 0; margin: 12px 0 0; }
.chat-side li { margin: 8px 0; }
.chat-main { background: var(--panel); border: 1px solid var(--border); border-radius: 16px; padding: 18px; min-height: 60vh; display: flex; flex-direction: column; }
.messages { flex: 1; overflow-y: auto; max-height: 62vh; display: grid; gap: 12px; padding: 6px 4px 14px; }
.chat-message { background: var(--panel-2); border: 1px solid var(--border); border-radius: 14px; padding: 12px 14px; }
.chat-message header { display: flex; justify-content: space-between; color: var(--muted); margin-bottom: 6px; }
.chat-message p { margin: 0; white-space: pre-wrap; }
.chat-form { display: grid; grid-template-columns: minmax(0, 1fr) auto; gap: 10px; margin-top: 12px; }
.chat-form textarea { min-height: 58px; resize: vertical; }
.chat-form button { align-self: end; }
.chat-side a.active { color: var(--text); font-weight: 700; }

.flash-stack { display: grid; gap: 8px; margin-bottom: 18px; }
.flash { background: var(--panel-2); border: 1px solid var(--border); border-left: 4px solid var(--accent-2); border-radius: 12px; padding: 12px 14px; }
.flash.error { border-left-color: var(--danger); }

.card-meta, .course-head-meta { display: flex; gap: 10px; align-items: center; flex-wrap: wrap; }
.enrolled-pill { color: var(--accent-2); border-color: rgba(34, 197, 94, .45); }
.course-actions { margin-top: 16px; display: flex; gap: 10px; align-items: center; flex-wrap: wrap; }
.course-actions form { margin: 0; }
.notice { background: rgba(56, 189, 248, .1); border: 1px solid rgba(56, 189, 248, .35); border-radius: 12px; padding: 12px 14px; color: var(--text); }
.muted-copy { color: var(--muted); }

.progress-block { margin-top: 16px; max-width: 560px; }
.progress-label { display: flex; justify-content: space-between; color: var(--muted); margin-bottom: 6px; }
.progress-track { height: 8px; background: var(--panel-2); border: 1px solid var(--border); border-radius: 999px; overflow: hidden; }
.progress-track span { display: block; height: 100%; background: linear-gradient(90deg, var(--accent), var(--accent-2)); border-radius: inherit; }

.page-head { max-width: 760px; margin-bottom: 24px; }
.dashboard-grid { display: grid; grid-template-columns: repeat(auto-fit, minmax(320px, 1fr)); gap: 16px; }
.dashboard-card, .empty-state, .recent-block { background: var(--panel); border: 1px solid var(--border); border-radius: 18px; padding: 20px; }
.dashboard-card-head { display: flex; justify-content: space-between; gap: 18px; align-items: start; }
.dashboard-card-head h2 { margin: 0 0 4px; }
.dashboard-card-head p { margin: 0; color: var(--muted); }
.dashboard-card-head strong { font-size: 28px; color: var(--accent); }
.dashboard-card .progress-track { margin-top: 16px; }
.dashboard-card-actions { display: flex; gap: 12px; align-items: center; flex-wrap: wrap; margin-top: 16px; }
.recent-block { margin-top: 20px; }
.recent-list { list-style: none; padding: 0; margin: 0; }
.recent-list li { display: flex; justify-content: space-between; gap: 16px; padding: 10px 0; border-bottom: 1px solid var(--border); }
.recent-list li:last-child { border-bottom: 0; }
.recent-list span { color: var(--muted); font-size: 13px; }
.error-page { max-width: 680px; padding: 60px 0; }

@media (max-width: 860px) {
  .chat-shell { grid-template-columns: 1fr; }
  .messages { max-height: 54vh; }
  .chat-form { grid-template-columns: 1fr; }
}

@media (max-width: 860px) {
  .topbar { flex-wrap: wrap; padding: 12px 16px; }
  .topbar nav { width: 100%; margin-left: 0; flex-wrap: wrap; gap: 8px 14px; }
  .search { order: 3; width: 100%; max-width: none; }
  .admin-panel, .admin-panel-compact { grid-template-columns: 1fr; }
  main { width: min(100% - 24px, 1180px); padding-top: 24px; }
  .lesson-layout { grid-template-columns: 1fr; }
}