:root {
  --bg: #0b0e17;
  --bg-2: #111624;
  --panel: #161c2d;
  --line: #27304a;
  --ink: #e9edf8;
  --muted: #94a3c4;
  --green: #3ddc97;
  --yellow: #ffd166;
  --pink: #ef476f;
  --blue: #5aa9ff;
  --radius: 14px;
  --mono: ui-monospace, SFMono-Regular, Menlo, Consolas, "Liberation Mono", monospace;
}

* { box-sizing: border-box; }

html { scroll-behavior: smooth; scroll-padding-top: 72px; }

body {
  margin: 0;
  background: var(--bg);
  color: var(--ink);
  font: 16px/1.65 system-ui, -apple-system, "Segoe UI", Roboto, sans-serif;
  -webkit-text-size-adjust: 100%;
}

a { color: var(--green); }
a:hover { color: #7af0ba; }

code, kbd, pre { font-family: var(--mono); }

code {
  background: #1d2439;
  border: 1px solid var(--line);
  border-radius: 5px;
  padding: 1px 5px;
  font-size: .88em;
  color: #cfe3ff;
  overflow-wrap: break-word;
}

kbd {
  background: #222a42;
  border: 1px solid var(--line);
  border-bottom-width: 2px;
  border-radius: 5px;
  padding: 1px 6px;
  font-size: .82em;
}

/* ---------- top bar ---------- */
.topbar {
  position: sticky;
  top: 0;
  z-index: 50;
  display: flex;
  align-items: center;
  gap: 16px;
  padding: 12px 20px;
  background: rgba(11, 14, 23, .9);
  backdrop-filter: blur(10px);
  border-bottom: 1px solid var(--line);
  flex-wrap: wrap;
}

.brand {
  font-weight: 800;
  color: var(--ink);
  text-decoration: none;
  letter-spacing: -.01em;
  margin-right: auto;
}
.brand-mark {
  color: var(--green);
  font-family: var(--mono);
  margin-right: 4px;
}

.topbar nav { display: flex; gap: 6px; flex-wrap: wrap; }
.topbar nav a {
  color: var(--muted);
  text-decoration: none;
  font-size: .92rem;
  font-weight: 600;
  padding: 6px 10px;
  border-radius: 8px;
}
.topbar nav a:hover { color: var(--ink); background: #1b2236; }

.nav-toggle {
  display: none;
  background: #1b2236;
  color: var(--ink);
  border: 1px solid var(--line);
  border-radius: 8px;
  font-size: 1.1rem;
  padding: 4px 11px;
  cursor: pointer;
}

/* ---------- hero ---------- */
.hero {
  display: grid;
  grid-template-columns: 1.05fr .95fr;
  gap: 48px;
  align-items: center;
  max-width: 1120px;
  margin: 0 auto;
  padding: 72px 20px 56px;
}

.eyebrow {
  color: var(--green);
  font-weight: 700;
  font-size: .8rem;
  letter-spacing: .09em;
  text-transform: uppercase;
  margin: 0 0 14px;
}

h1 {
  font-size: clamp(2rem, 5vw, 3.1rem);
  line-height: 1.08;
  letter-spacing: -.025em;
  margin: 0 0 18px;
}

.lede { color: #c3cee6; font-size: 1.08rem; margin: 0 0 28px; }

.hero-cta { display: flex; gap: 12px; flex-wrap: wrap; }

.btn {
  display: inline-block;
  padding: 12px 22px;
  border-radius: 10px;
  font-weight: 700;
  text-decoration: none;
  border: 1px solid transparent;
  cursor: pointer;
  font-size: .97rem;
}
.btn-primary { background: var(--green); color: #07200f; }
.btn-primary:hover { background: #63e9ae; color: #07200f; }
.btn-ghost { border-color: var(--line); color: var(--ink); background: #151b2b; }
.btn-ghost:hover { background: #1d2540; color: var(--ink); }

.hero-facts {
  display: flex;
  gap: 28px;
  list-style: none;
  padding: 0;
  margin: 32px 0 0;
  color: var(--muted);
  font-size: .9rem;
}
.hero-facts strong {
  display: block;
  color: var(--yellow);
  font-size: 1.5rem;
  line-height: 1.1;
}

.code-card {
  background: #0d1220;
  border: 1px solid var(--line);
  border-radius: var(--radius);
  padding: 16px 18px 20px;
  box-shadow: 0 24px 60px #0009;
  overflow-x: auto;
}
.code-dots { display: flex; gap: 6px; margin-bottom: 12px; }
.code-dots i {
  width: 10px; height: 10px; border-radius: 50%;
  background: #2b3451;
}
.code-dots i:first-child { background: var(--pink); }
.code-dots i:nth-child(2) { background: var(--yellow); }
.code-dots i:nth-child(3) { background: var(--green); }
.code-card pre { margin: 0; font-size: .82rem; line-height: 1.65; color: #d7e2f5; }
.c-t { color: #ff8fab; }
.c-a { color: var(--yellow); }
.c-s { color: #9ae6b4; }
.c-k { color: #c4a3ff; }
.c-f { color: var(--blue); }
.c-n { color: #ffb86c; }

/* ---------- bands ---------- */
.band {
  max-width: 1120px;
  margin: 0 auto;
  padding: 64px 20px;
}
.band.alt {
  max-width: none;
  background: var(--bg-2);
  border-top: 1px solid var(--line);
  border-bottom: 1px solid var(--line);
}
.band.alt > * { max-width: 1080px; margin-left: auto; margin-right: auto; }

h2 {
  font-size: clamp(1.5rem, 3.4vw, 2.1rem);
  letter-spacing: -.02em;
  margin: 0 0 10px;
}
h2::after {
  content: "";
  display: block;
  width: 54px;
  height: 3px;
  background: var(--green);
  border-radius: 2px;
  margin-top: 12px;
}
.band-lede { color: var(--muted); max-width: 70ch; margin: 18px 0 34px; }
.sub { margin: 48px 0 16px; font-size: 1.2rem; }
.note { color: var(--muted); font-size: .92rem; margin-top: 26px; }

/* ---------- cards ---------- */
.cards {
  display: grid;
  grid-template-columns: repeat(auto-fit, minmax(240px, 1fr));
  gap: 18px;
  margin-top: 30px;
}
.card {
  background: var(--panel);
  border: 1px solid var(--line);
  border-radius: var(--radius);
  padding: 22px;
}
.card h3 { margin: 0 0 8px; font-size: 1.05rem; }
.card p { margin: 0; color: #bac6e0; font-size: .95rem; }
.step {
  display: inline-grid;
  place-items: center;
  width: 30px; height: 30px;
  border-radius: 9px;
  background: var(--green);
  color: #07200f;
  font-weight: 800;
  font-size: .9rem;
  margin-bottom: 12px;
}

/* ---------- lessons ---------- */
.lesson {
  background: var(--panel);
  border: 1px solid var(--line);
  border-radius: 18px;
  padding: 26px 26px 30px;
  margin-bottom: 22px;
}
.lesson header { display: flex; align-items: baseline; gap: 14px; margin-bottom: 14px; }
.lesson header h3 { margin: 0; font-size: 1.3rem; letter-spacing: -.015em; }
.lnum {
  font-family: var(--mono);
  font-size: 1.5rem;
  font-weight: 700;
  color: #2f3b5c;
}
.lesson p { color: #c3cee6; }
.lesson > p:first-of-type { margin-top: 0; }

.bullets { color: #c3cee6; padding-left: 20px; margin: 14px 0; }
.bullets li { margin-bottom: 7px; }
.bullets.tight li { margin-bottom: 4px; }

.steps { color: #c3cee6; padding-left: 22px; }
.steps li { margin-bottom: 9px; }
.steps.big li { margin-bottom: 14px; font-size: 1.03rem; }

.tip {
  background: #14271f;
  border-left: 3px solid var(--green);
  border-radius: 0 8px 8px 0;
  padding: 10px 14px;
  font-size: .93rem;
  margin: 18px 0 0;
}

.snippet {
  background: #0d1220;
  border: 1px solid var(--line);
  border-radius: 10px;
  padding: 14px 16px;
  overflow-x: auto;
  font-size: .85rem;
  line-height: 1.6;
  color: #d7e2f5;
  margin: 14px 0;
}

/* ---------- tables ---------- */
.table-wrap { overflow-x: auto; margin: 16px 0; }
table {
  width: 100%;
  border-collapse: collapse;
  font-size: .93rem;
  min-width: 420px;
}
th, td {
  text-align: left;
  padding: 10px 12px;
  border-bottom: 1px solid var(--line);
  vertical-align: top;
}
th { color: var(--green); font-size: .8rem; text-transform: uppercase; letter-spacing: .06em; }
td { color: #c3cee6; }
tbody tr:hover { background: #1a2135; }

/* ---------- live editors ---------- */
.editor {
  margin: 18px 0 0;
  border: 1px solid var(--line);
  border-radius: 12px;
  overflow: hidden;
  background: #0d1220;
}
.editor-bar {
  display: flex;
  align-items: center;
  gap: 10px;
  padding: 8px 10px;
  background: #151c2e;
  border-bottom: 1px solid var(--line);
}
.editor-bar .label {
  font-size: .74rem;
  letter-spacing: .08em;
  text-transform: uppercase;
  color: var(--muted);
  font-weight: 700;
  margin-right: auto;
}
.editor-bar button {
  background: #222b44;
  color: var(--ink);
  border: 1px solid var(--line);
  border-radius: 7px;
  padding: 5px 12px;
  font-size: .82rem;
  font-weight: 700;
  cursor: pointer;
}
.editor-bar button:hover { background: #2c3755; }
.editor-bar .run { background: var(--green); color: #07200f; border-color: transparent; }
.editor-bar .run:hover { background: #63e9ae; }

.editor-panes { display: grid; grid-template-columns: 1fr 1fr; }
.editor textarea {
  width: 100%;
  min-height: 260px;
  border: 0;
  border-right: 1px solid var(--line);
  background: #0d1220;
  color: #d7e2f5;
  font-family: var(--mono);
  font-size: .82rem;
  line-height: 1.6;
  padding: 14px;
  resize: vertical;
  tab-size: 2;
  display: block;
}
.editor textarea:focus { outline: 2px solid var(--green); outline-offset: -2px; }
.editor iframe {
  width: 100%;
  min-height: 260px;
  border: 0;
  background: #fff;
  display: block;
}

/* ---------- demo game ---------- */
.game-wrap {
  display: grid;
  grid-template-columns: 1.4fr .9fr;
  gap: 26px;
  align-items: start;
  margin-top: 26px;
}
.game-stage {
  background: #0d1220;
  border: 1px solid var(--line);
  border-radius: 16px;
  padding: 14px;
}
#gameCanvas {
  width: 100%;
  height: auto;
  display: block;
  border-radius: 10px;
  background: #060913;
  touch-action: manipulation;
  cursor: pointer;
}
.touch-controls {
  display: flex;
  gap: 10px;
  margin-top: 12px;
}
.tc {
  flex: 1;
  background: #1d2540;
  color: var(--ink);
  border: 1px solid var(--line);
  border-radius: 10px;
  padding: 14px 0;
  font-size: 1.05rem;
  font-weight: 700;
  cursor: pointer;
  user-select: none;
  -webkit-user-select: none;
  touch-action: manipulation;
}
.tc:active { background: var(--green); color: #07200f; }
.tc-jump { flex: 1.4; }

.game-side {
  background: var(--panel);
  border: 1px solid var(--line);
  border-radius: 16px;
  padding: 22px;
}
.game-side h3 { margin: 0 0 12px; font-size: 1.1rem; }
.game-side p { color: #bac6e0; font-size: .94rem; }

.scoreboard { display: flex; gap: 12px; margin-top: 18px; }
.scoreboard > div {
  flex: 1;
  background: #0f1526;
  border: 1px solid var(--line);
  border-radius: 10px;
  padding: 12px;
  text-align: center;
}
.sb-label {
  display: block;
  font-size: .7rem;
  letter-spacing: .1em;
  text-transform: uppercase;
  color: var(--muted);
  font-weight: 700;
}
.sb-value {
  display: block;
  font-family: var(--mono);
  font-size: 1.6rem;
  font-weight: 700;
  color: var(--yellow);
}

/* ---------- reference ---------- */
.ref-grid {
  display: grid;
  grid-template-columns: repeat(auto-fit, minmax(290px, 1fr));
  gap: 18px;
  margin-top: 28px;
}
.ref {
  background: var(--panel);
  border: 1px solid var(--line);
  border-radius: var(--radius);
  padding: 20px;
}
.ref h3 { margin: 0 0 10px; font-size: 1.02rem; color: var(--green); }
.ref .snippet { margin: 0; background: #0d1220; }

.finish { padding-bottom: 72px; }

footer {
  border-top: 1px solid var(--line);
  padding: 32px 20px 44px;
  text-align: center;
}
footer p {
  max-width: 62ch;
  margin: 0 auto;
  color: var(--muted);
  font-size: .9rem;
}

/* ---------- responsive ---------- */
@media (max-width: 900px) {
  .hero { grid-template-columns: 1fr; gap: 34px; padding-top: 48px; }
  .game-wrap { grid-template-columns: 1fr; }
  .editor-panes { grid-template-columns: 1fr; }
  .editor textarea { border-right: 0; border-bottom: 1px solid var(--line); min-height: 220px; }
  .editor iframe { min-height: 230px; }
}

@media (max-width: 680px) {
  .nav-toggle { display: block; }
  .topbar nav {
    display: none;
    width: 100%;
    flex-direction: column;
    gap: 2px;
    padding-top: 8px;
  }
  .topbar nav.open { display: flex; }
  .band { padding: 44px 16px; }
  .lesson { padding: 20px 16px 24px; border-radius: 14px; }
  .hero { padding: 36px 16px 40px; }
  .hero-facts { gap: 20px; }
  .lesson header { gap: 10px; }
  .lnum { font-size: 1.2rem; }
}