:root{
  --bg:#0d1117; --panel:#161b22; --panel2:#1c2230; --border:#30363d;
  --text:#e6edf3; --muted:#8b949e; --gold:#f0b429; --green:#3fb950;
  --red:#f85149; --blue:#388bfd;
}
html[data-theme="light"]{
  --bg:#f3f5f8; --panel:#ffffff; --panel2:#eef1f5; --border:#d7dde5;
  --text:#1b1f24; --muted:#5b6672; --gold:#9a6a00; --green:#1a7f37;
  --red:#cf222e; --blue:#0969da;
}
html[data-theme="light"] .keybox{color:#1a7f37}
html[data-theme="light"] .btn{color:#fff}
html[data-theme="light"] .badge.lvl1{background:#e7edf6;color:#3b5b86}
html[data-theme="light"] .badge.lvl2{background:#e3f3e9;color:#1a7f37}
html[data-theme="light"] .badge.lvl3{background:#fbf0d8;color:#8a5a00}
*{box-sizing:border-box;margin:0;padding:0}
body{background:var(--bg);color:var(--text);
  font-family:-apple-system,BlinkMacSystemFont,"Segoe UI",Roboto,sans-serif;
  line-height:1.5;font-size:15px}
a{color:var(--blue);text-decoration:none}
a:hover{text-decoration:underline}
.container{max-width:980px;margin:0 auto;padding:24px 20px}
.narrow{max-width:520px}

/* header */
.topbar{background:var(--panel);border-bottom:1px solid var(--border)}
.topbar .inner{max-width:980px;margin:0 auto;padding:14px 20px;
  display:flex;align-items:center;gap:18px;flex-wrap:wrap}
.brand{font-weight:700;color:var(--gold);font-size:18px}
.topbar nav{display:flex;gap:16px;flex-wrap:wrap}
.topbar nav a{color:var(--muted);font-size:14px}
.topbar nav a:hover,.topbar nav a.active{color:var(--text);text-decoration:none}
.topbar .spacer{margin-left:auto}

/* cards */
.card{background:var(--panel);border:1px solid var(--border);border-radius:12px;
  padding:22px 24px;margin-bottom:18px}
.card h2{font-size:17px;margin-bottom:12px}
.card h3{font-size:15px;color:var(--muted);margin-bottom:8px}
.muted{color:var(--muted)}
.small{font-size:13px}
.mono{font-family:ui-monospace,Menlo,monospace}

/* grid of courses */
.grid{display:grid;grid-template-columns:repeat(auto-fill,minmax(260px,1fr));gap:16px}
.tile{background:var(--panel);border:1px solid var(--border);border-radius:12px;
  padding:20px;display:block;transition:border-color .15s}
.tile:hover{border-color:var(--gold);text-decoration:none}
.tile .t{font-size:16px;font-weight:600;color:var(--text);margin-bottom:6px}

/* badges */
.badge{display:inline-block;padding:2px 10px;border-radius:20px;font-size:12px;font-weight:600}
.badge.lvl1{background:#1f2937;color:#9cb3d6}
.badge.lvl2{background:#243b2a;color:#7ee2a0}
.badge.lvl3{background:#3a2e16;color:var(--gold)}
.badge.ok{background:#16331d;color:var(--green)}
.badge.warn{background:#3a2e16;color:var(--gold)}
.badge.off{background:#3a1d1d;color:var(--red)}

/* lesson list */
.lesson-row{display:flex;align-items:center;gap:12px;padding:12px 0;border-bottom:1px solid var(--border)}
.lesson-row:last-child{border-bottom:none}
.lesson-row .num{width:28px;height:28px;border-radius:50%;background:var(--panel2);
  display:flex;align-items:center;justify-content:center;font-size:13px;color:var(--muted);flex:none}
.locked{opacity:.5}

/* forms */
label{display:block;font-size:13px;color:var(--muted);margin:14px 0 6px}
input,select,textarea{width:100%;background:var(--bg);border:1px solid var(--border);
  border-radius:8px;color:var(--text);font-size:15px;padding:10px 12px;outline:none}
input:focus,select:focus,textarea:focus{border-color:var(--gold)}
textarea{min-height:90px;resize:vertical;font-family:inherit}
.row{display:flex;gap:12px;flex-wrap:wrap}
.row>*{flex:1;min-width:160px}
.check{display:flex;align-items:center;gap:8px;margin-top:14px}
.check input{width:auto}

/* buttons */
.btn{display:inline-block;background:var(--gold);color:#0d1117;font-weight:700;
  border:none;border-radius:8px;padding:11px 18px;cursor:pointer;font-size:15px}
.btn:hover{opacity:.9;text-decoration:none}
.btn.sec{background:var(--panel2);color:var(--text);border:1px solid var(--border)}
.btn.danger{background:#3a1d1d;color:var(--red);border:1px solid #6e2a2a}
.btn.sm{padding:7px 12px;font-size:13px}
.btn.full{width:100%;text-align:center}

/* key box */
.keybox{background:var(--bg);border:1px solid var(--border);border-radius:8px;
  padding:14px 16px;font-family:ui-monospace,Menlo,monospace;font-size:18px;
  color:var(--green);letter-spacing:1px;word-break:break-all;cursor:pointer}
.keybox:hover{border-color:var(--green)}
.kv{display:flex;justify-content:space-between;gap:16px;padding:9px 0;border-bottom:1px solid var(--border)}
.kv:last-child{border-bottom:none}
.kv .k{color:var(--muted);font-size:13px}
.kv .v{font-family:ui-monospace,Menlo,monospace;text-align:right;word-break:break-all}

/* flash */
.flash{padding:11px 16px;border-radius:8px;margin-bottom:14px;font-size:14px}
.flash.success{background:#16331d;color:var(--green);border:1px solid #238636}
.flash.error{background:#3a1d1d;color:var(--red);border:1px solid #6e2a2a}

/* table */
table{width:100%;border-collapse:collapse;font-size:14px}
th{text-align:left;color:var(--muted);font-size:12px;font-weight:600;
  padding:8px 10px;border-bottom:1px solid var(--border)}
td{padding:10px;border-bottom:1px solid var(--panel2)}
tr:last-child td{border-bottom:none}

.video{position:relative;padding-bottom:56.25%;height:0;border-radius:10px;overflow:hidden;background:#000}
.video iframe{position:absolute;inset:0;width:100%;height:100%;border:0}
.note{background:var(--panel2);border:1px solid var(--border);border-radius:8px;
  padding:10px 14px;font-size:13px;color:var(--muted);margin-top:12px}
.toast{position:fixed;bottom:24px;left:50%;transform:translateX(-50%);
  background:#238636;color:#fff;padding:9px 18px;border-radius:8px;font-size:13px;display:none}