:root {
  --bg0: #0c0e12;
  --bg1: #161b22;
  --ink: #e6edf3;
  --muted: #8b949e;
  --cyan: #55ffff;
  --magenta: #ff55ff;
  --frame: #30363d;
  --font-display: "IBM Plex Mono", "Courier New", Courier, monospace;
  --font-body: "IBM Plex Sans", "Segoe UI", sans-serif;
}

@font-face {
  font-family: "IBM Plex Mono";
  font-style: normal;
  font-weight: 400;
  font-display: swap;
  src: local("IBM Plex Mono"), local("Courier New");
}

*,
*::before,
*::after {
  box-sizing: border-box;
}

html,
body {
  margin: 0;
  min-height: 100%;
  background:
    radial-gradient(ellipse 120% 80% at 50% -20%, #1a2332 0%, transparent 55%),
    linear-gradient(180deg, var(--bg1), var(--bg0));
  color: var(--ink);
  font-family: var(--font-body);
}

.page {
  max-width: min(100%, 120rem);
  margin: 0 auto;
  padding: 1.25rem 1.25rem 3rem;
}

.header {
  text-align: center;
  margin-bottom: 1.25rem;
}

.header h1 {
  margin: 0;
  font-family: var(--font-display);
  font-size: clamp(1.75rem, 5vw, 2.75rem);
  font-weight: 700;
  letter-spacing: 0.06em;
  color: var(--cyan);
  text-shadow: 0 0 24px rgba(85, 255, 255, 0.25);
}

.tagline {
  margin: 0.5rem 0 0;
  color: var(--muted);
  font-size: 0.95rem;
}

.stage-wrap {
  display: flex;
  flex-direction: column;
  align-items: center;
  gap: 0.75rem;
}

.stage {
  position: relative;
  background: #000;
  border: 2px solid var(--frame);
  box-shadow:
    0 0 0 1px #000,
    0 12px 40px rgba(0, 0, 0, 0.55);
  line-height: 0;
  max-width: 100%;
  touch-action: none;
  -webkit-user-select: none;
  user-select: none;
}

.stage.crt::after {
  content: "";
  pointer-events: none;
  position: absolute;
  inset: 0;
  background: repeating-linear-gradient(
    to bottom,
    rgba(0, 0, 0, 0.18) 0,
    rgba(0, 0, 0, 0.18) 1px,
    transparent 1px,
    transparent 3px
  );
  mix-blend-mode: multiply;
  opacity: 0.65;
}

.stage.crt::before {
  content: "";
  pointer-events: none;
  position: absolute;
  inset: 0;
  background: radial-gradient(ellipse at center, transparent 55%, rgba(0, 0, 0, 0.35) 100%);
}

#game {
  display: block;
  width: 320px;
  height: 200px;
  image-rendering: pixelated;
  image-rendering: crisp-edges;
  background: #000;
  touch-action: none;
}

.controls-hint {
  display: flex;
  flex-direction: column;
  align-items: center;
  gap: 0.5rem;
  font-family: var(--font-display);
  font-size: 0.8rem;
  color: var(--muted);
}

.controls-keys,
.controls-toggles {
  display: flex;
  flex-wrap: wrap;
  justify-content: center;
  gap: 0.75rem 1.25rem;
}

kbd {
  display: inline-block;
  padding: 0.1em 0.4em;
  border: 1px solid var(--frame);
  border-bottom-width: 2px;
  border-radius: 3px;
  background: #21262d;
  color: var(--ink);
  font-family: inherit;
  font-size: 0.85em;
}

.crt-toggle {
  display: inline-flex;
  align-items: center;
  gap: 0.35rem;
  cursor: pointer;
  user-select: none;
}

.ctrl-btn {
  appearance: none;
  margin: 0;
  padding: 0.2em 0.55em;
  border: 1px solid var(--frame);
  border-radius: 3px;
  background: #21262d;
  color: var(--ink);
  font-family: inherit;
  font-size: inherit;
  cursor: pointer;
  user-select: none;
}

.ctrl-btn:active {
  border-color: var(--cyan);
  color: var(--cyan);
}

/* Immersive / “fullscreen” — hides chrome; useful on iOS (no element Fullscreen API). */
body.immersive {
  overflow: hidden;
  background: #000;
}

body.immersive .page {
  max-width: none;
  padding: 0;
  min-height: 100dvh;
  min-height: 100svh;
  display: flex;
  flex-direction: column;
  justify-content: center;
}

body.immersive .header,
body.immersive .about,
body.immersive .footer,
body.immersive .controls-keys {
  display: none;
}

body.immersive .stage-wrap {
  width: 100%;
  gap: 0.5rem;
}

body.immersive .stage {
  width: 100%;
  max-width: 100vw;
  border: none;
  box-shadow: none;
}

body.immersive .controls-hint {
  padding: 0.35rem 0.75rem calc(0.35rem + env(safe-area-inset-bottom, 0));
}

body.immersive .controls-toggles {
  gap: 0.65rem 1rem;
}

.about {
  max-width: 40rem;
  margin: 2rem auto 0;
  padding-top: 1.5rem;
  border-top: 1px solid var(--frame);
}

.about h2 {
  margin: 0 0 0.75rem;
  font-family: var(--font-display);
  font-size: 1rem;
  color: var(--magenta);
  letter-spacing: 0.04em;
}

.about p {
  margin: 0 0 0.75rem;
  color: var(--muted);
  line-height: 1.55;
  font-size: 0.95rem;
}

.about a {
  color: var(--cyan);
}

.footer {
  margin-top: 1.5rem;
  text-align: center;
  font-size: 0.75rem;
  color: #6e7681;
}

.footer p {
  margin: 0;
}

.footer .build-id {
  margin-top: 0.4rem;
  font-family: var(--font-display);
  font-size: 0.7rem;
  letter-spacing: 0.04em;
  color: #484f58;
}

.footer .build-id a {
  color: #6e7681;
  text-decoration: none;
}

.footer .build-id a:hover {
  color: var(--cyan);
}

/* Source listing */
.source-nav {
  margin: 0.75rem 0 0;
  font-family: var(--font-display);
  font-size: 0.85rem;
  color: var(--muted);
}

.source-nav a {
  color: var(--cyan);
}

.listing-wrap {
  max-width: 52rem;
  margin: 0 auto;
}

.listing {
  margin: 0;
  padding: 1rem 1.1rem;
  overflow-x: auto;
  background: #0a0c10;
  border: 1px solid var(--frame);
  box-shadow: 0 12px 40px rgba(0, 0, 0, 0.45);
  font-family: var(--font-display);
  font-size: 0.8rem;
  line-height: 1.45;
  color: var(--ink);
  tab-size: 4;
}

.listing code {
  font-family: inherit;
}

.listing .ln {
  color: #6e7681;
  user-select: none;
}

.listing .kw {
  color: var(--cyan);
}

.listing .st {
  color: #ffcc66;
}

.listing .cm {
  color: #7a8490;
  font-style: italic;
}

.listing .nu {
  color: var(--magenta);
}

.listing .id {
  color: #c9d1d9;
}

.listing-error {
  color: #ff7b72;
}

@media (max-width: 720px) {
  .page {
    padding: 0.75rem 0 2rem;
  }

  .header,
  .controls-hint,
  .about,
  .footer,
  .listing-wrap {
    padding-left: 0.75rem;
    padding-right: 0.75rem;
  }

  .listing {
    font-size: 0.72rem;
  }

  .stage-wrap {
    width: 100%;
    gap: 0.5rem;
  }

  .stage {
    width: 100%;
    max-width: 100vw;
    border-left: none;
    border-right: none;
    box-shadow:
      0 -1px 0 #000,
      0 1px 0 #000,
      0 12px 40px rgba(0, 0, 0, 0.55);
  }

  #game {
    width: 100%;
    height: auto;
  }

  .header {
    margin-bottom: 0.75rem;
  }

  .header h1 {
    font-size: clamp(1.35rem, 7vw, 2rem);
  }

  .tagline {
    font-size: 0.85rem;
  }
}