:root {
  --bg: #0f1419;
  --panel: #171e26;
  --panel2: #1e2731;
  --line: #2a3542;
  --text: #dce3ea;
  --muted: #8a99a8;
  --accent: #3ec7ff;
  --ok: #4fd18b;
  --warn: #ffb547;
  --oled: #7fd8ff;
  font-family: system-ui, -apple-system, "Segoe UI", Roboto, sans-serif;
}
* { box-sizing: border-box; }
body { margin: 0; background: var(--bg); color: var(--text); line-height: 1.6; }
a { color: var(--accent); text-decoration: none; }
a:hover { text-decoration: underline; }
code { background: var(--panel2); padding: 1px 6px; border-radius: 4px; font-size: .92em; }

.top { display: flex; align-items: center; justify-content: space-between; gap: 16px;
  padding: 14px 28px; border-bottom: 1px solid var(--line); background: var(--panel);
  position: sticky; top: 0; z-index: 10; flex-wrap: wrap; }
.logo { font-weight: 700; font-size: 20px; color: var(--text); }
.logo span { color: var(--accent); }
.top nav a { margin-left: 22px; color: var(--muted); font-weight: 500; }
.top nav a.active, .top nav a:hover { color: var(--text); text-decoration: none; }

main { max-width: 1080px; margin: 0 auto; padding: 32px 24px 60px; }
.foot { text-align: center; color: var(--muted); font-size: 13px; padding: 24px; border-top: 1px solid var(--line); }

h1 { font-size: 34px; margin: 0 0 8px; line-height: 1.2; }
h2 { font-size: 22px; margin: 36px 0 12px; }
h3 { font-size: 17px; margin: 24px 0 8px; }
.lead { color: var(--muted); font-size: 18px; margin: 0 0 24px; }

.hero { display: grid; grid-template-columns: 1.2fr 1fr; gap: 32px; align-items: center; }
.btn { display: inline-block; background: var(--accent); color: #04121b; font-weight: 700;
  padding: 10px 20px; border-radius: 8px; border: 0; cursor: pointer; font-size: 15px; }
.btn:hover { text-decoration: none; filter: brightness(1.1); }
.btn.ghost { background: transparent; color: var(--text); border: 1px solid var(--line); }

.facts { display: grid; grid-template-columns: repeat(auto-fill, minmax(150px, 1fr)); gap: 12px; margin: 20px 0; }
.fact { background: var(--panel); border: 1px solid var(--line); border-radius: 10px; padding: 12px 14px; }
.fact b { display: block; font-size: 18px; }
.fact span { color: var(--muted); font-size: 13px; }

.progress { height: 8px; background: var(--panel2); border-radius: 4px; overflow: hidden; margin: 8px 0 20px; }
.progress div { height: 100%; background: var(--ok); }

.cards { display: grid; grid-template-columns: repeat(auto-fill, minmax(300px, 1fr)); gap: 14px; }
.card { display: block; background: var(--panel); border: 1px solid var(--line); border-radius: 12px;
  padding: 16px 18px; color: var(--text); transition: border-color .15s, transform .15s; }
.card:hover { border-color: var(--accent); text-decoration: none; transform: translateY(-2px); }
.card .num { color: var(--accent); font-weight: 700; font-size: 13px; }
.card h3 { margin: 4px 0 6px; }
.card p { margin: 0; color: var(--muted); font-size: 14px; }
.card .done { color: var(--ok); font-size: 13px; font-weight: 600; margin-top: 8px; display: block; }
.tags { margin-top: 8px; }
.tag { display: inline-block; font-size: 12px; background: var(--panel2); color: var(--muted);
  padding: 1px 8px; border-radius: 10px; margin: 2px 4px 0 0; }

.lesson { display: grid; grid-template-columns: minmax(0, 1fr) 300px; gap: 32px; }
.side { position: sticky; top: 80px; align-self: start; }
.box { background: var(--panel); border: 1px solid var(--line); border-radius: 12px; padding: 16px; margin-bottom: 16px; }
.box h4 { margin: 0 0 10px; font-size: 14px; color: var(--muted); text-transform: uppercase; letter-spacing: .05em; }
.box ul { margin: 0; padding-left: 18px; }
.crumbs { color: var(--muted); font-size: 14px; margin-bottom: 8px; }

.note, .warn { border-left: 4px solid var(--accent); background: var(--panel); padding: 10px 16px;
  border-radius: 0 8px 8px 0; margin: 16px 0; }
.warn { border-color: var(--warn); }
.note p, .warn p { margin: 4px 0; }

pre { position: relative; background: #0a0e12; border: 1px solid var(--line); border-radius: 10px;
  padding: 16px; overflow-x: auto; font-size: 14px; line-height: 1.5; margin: 12px 0; }
pre code { background: none; padding: 0; font-family: "JetBrains Mono", "Fira Code", Consolas, monospace; }
.copy { position: absolute; top: 8px; right: 8px; background: var(--panel2); color: var(--muted);
  border: 1px solid var(--line); border-radius: 6px; padding: 3px 10px; font-size: 12px; cursor: pointer; }
.copy:hover { color: var(--text); }
.c-com { color: #6a7d8f; font-style: italic; }
.c-str { color: #a5d86e; }
.c-kw { color: #ff8c6b; }
.c-num { color: #d6a6ff; }
.c-pre { color: #ffd166; }

table { width: 100%; border-collapse: collapse; margin: 12px 0; font-size: 14px; }
th, td { text-align: left; padding: 8px 10px; border-bottom: 1px solid var(--line); vertical-align: top; }
th { color: var(--muted); font-weight: 600; }

.oled-wrap { background: #050607; border-radius: 10px; padding: 14px; text-align: center; border: 1px solid var(--line); }
.oled-wrap canvas { image-rendering: pixelated; width: 100%; max-width: 288px; background: #000; border-radius: 3px; }
.oled-wrap small { display: block; color: var(--muted); margin-top: 6px; font-size: 12px; }

.wiring { display: grid; grid-template-columns: auto 1fr; gap: 4px 14px; font-size: 14px; }
.wiring b { color: var(--accent); white-space: nowrap; }

.navlinks { display: flex; justify-content: space-between; gap: 12px; margin-top: 40px; flex-wrap: wrap; }
.board svg { width: 100%; height: auto; }

@media (max-width: 860px) {
  .hero, .lesson { grid-template-columns: 1fr; }
  .side { position: static; }
  .top nav a { margin: 0 16px 0 0; }
}