:root {
  --accent: #0f766e;
  --accent-dark: #134e4a;
  --accent-soft: #ccfbf1;
  --navy: #0f172a;
  --ink: #020817;
  --text: #1e293b;
  --muted: #64748b;
  --line: #e2e8f0;
}
* { box-sizing: border-box; }
body { margin: 0; font-family: system-ui, -apple-system, "Segoe UI", Roboto, sans-serif; color: var(--text); line-height: 1.6; background: #fff; }
a { color: var(--accent); text-decoration: none; }
a:hover { text-decoration: underline; }
header { background: var(--navy); border-bottom: 3px solid var(--accent); }
header .bar, main, footer .bar { max-width: 1080px; margin: 0 auto; padding: 0 1.25rem; }
header .bar { display: flex; align-items: center; justify-content: space-between; height: 4rem; }
.brand { font-weight: 700; font-size: 1.15rem; color: #fff; }
.brand:hover { text-decoration: none; }
nav a { margin-left: 1.25rem; color: #cbd5e1; }
nav a.button, .button { background: var(--accent); color: #fff; padding: .5rem 1rem; border-radius: .4rem; border: 0; font: inherit; cursor: pointer; }
header .button, .hero .button { background: var(--accent-soft); color: var(--navy); }
.hero { background: var(--navy); padding: 3.5rem 0; border-bottom: 1px solid var(--ink); }
.hero .inner { max-width: 1080px; margin: 0 auto; padding: 0 1.25rem; }
.hero .eyebrow { margin: 0 0 .5rem; font-size: .9rem; font-weight: 600; letter-spacing: .08em; text-transform: uppercase; color: var(--accent-soft); }
.hero h1 { font-size: 2.3rem; margin: 0 0 .75rem; color: #fff; }
.hero p { font-size: 1.15rem; max-width: 40rem; color: #cbd5e1; }
h1, h2, h3 { color: var(--navy); }
.grid { display: grid; grid-template-columns: repeat(auto-fill, minmax(240px, 1fr)); gap: 1.5rem; margin: 2.5rem 0; }
.card { display: block; border: 1px solid var(--line); border-radius: .6rem; overflow: hidden; color: var(--text); }
.card:hover { text-decoration: none; border-color: var(--accent); }
.card img { width: 100%; display: block; aspect-ratio: 16 / 9; }
.card .body { padding: 1rem; }
.card h3 { margin: 0 0 .35rem; font-size: 1.05rem; }
.meta { color: var(--muted); font-size: .9rem; }
.course { display: grid; grid-template-columns: 2fr 1fr; gap: 2rem; margin: 2.5rem 0; }
.player { width: 100%; aspect-ratio: 16 / 9; border-radius: .6rem; background: var(--ink); display: block; }
.lessons { border: 1px solid var(--line); border-radius: .6rem; padding: 1rem 1.25rem; }
.lessons ol { padding-left: 1.2rem; margin: .5rem 0 0; }
.auth { max-width: 24rem; margin: 3rem auto; border: 1px solid var(--line); border-top: 3px solid var(--accent); border-radius: .6rem; padding: 2rem; }
.auth h1 { margin-top: 0; font-size: 1.6rem; }
.auth label { display: block; margin: 1rem 0 .3rem; font-weight: 600; }
.auth input { width: 100%; padding: .6rem; border: 1px solid var(--line); border-radius: .4rem; font: inherit; }
.auth .button { width: 100%; margin-top: 1.5rem; padding: .7rem; }
.error { background: #fef2f2; color: #991b1b; border: 1px solid #fecaca; border-radius: .4rem; padding: .6rem .8rem; }
.notice { background: var(--accent-soft); color: var(--navy); border-radius: .4rem; padding: .6rem .8rem; }
footer { background: var(--ink); color: #94a3b8; margin-top: 3rem; padding: 1.5rem 0; font-size: .9rem; }
footer a { color: #cbd5e1; }
@media (max-width: 760px) { .course { grid-template-columns: 1fr; } nav a:not(.button) { display: none; } }