/* Neon Snake Arena — all colors verified at 4.5:1 or better against the
   #0a0a12 background (lowest pair in use is 6.87:1). */

:root {
  --bg: #0a0a12;
  --surface: #12121e;
  --surface-2: #171726;
  --line: rgba(255, 255, 255, 0.09);
  --line-soft: rgba(255, 255, 255, 0.06);
  --text: #eceffd;
  --muted: #a2abcf;
  --dim: #8e97bd;
  --cyan: #3ee9f5;
  --magenta: #ff5cf0;
  --violet: #b98cff;
  --focus: #ffd166;

  --r-sm: 4px;
  --r-md: 8px;
  --r-lg: 12px;
  --sp-1: 4px;
  --sp-2: 8px;
  --sp-3: 12px;
  --sp-4: 16px;
  --sp-5: 24px;
  --sp-6: 32px;
  --sp-7: 48px;

  --mono: ui-monospace, SFMono-Regular, "SF Mono", Menlo, Consolas,
    "Liberation Mono", "Courier New", monospace;
  --sans: system-ui, -apple-system, "Segoe UI", Roboto, "Helvetica Neue",
    Arial, "Noto Sans", sans-serif;
}

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

html { -webkit-text-size-adjust: 100%; }

body {
  margin: 0;
  background: var(--bg);
  color: var(--text);
  font-family: var(--sans);
  font-size: 16px;
  line-height: 1.65;
  /* A single static radial wash. No animation, nothing that flashes. */
  background-image:
    radial-gradient(900px 520px at 18% -10%, rgba(62, 233, 245, 0.07), transparent 65%),
    radial-gradient(760px 460px at 88% 4%, rgba(255, 92, 240, 0.06), transparent 62%);
  background-attachment: fixed;
}

/* CRT scanline overlay — 8% opacity, static, non-interactive. */
body::after {
  content: "";
  position: fixed;
  inset: 0;
  z-index: 50;
  pointer-events: none;
  opacity: 0.08;
  background: repeating-linear-gradient(
    to bottom,
    rgba(255, 255, 255, 0.9) 0,
    rgba(255, 255, 255, 0.9) 1px,
    transparent 1px,
    transparent 3px
  );
}

.container {
  max-width: 1100px;
  margin: 0 auto;
  padding: 0 var(--sp-5);
}

@media (max-width: 768px) {
  .container { padding: 0 var(--sp-4); }
}

/* --------------------------------------------------------- accessibility */

a { color: var(--cyan); text-decoration-thickness: 1px; text-underline-offset: 3px; }
a:hover { color: var(--text); }

:focus-visible {
  outline: 3px solid var(--focus);
  outline-offset: 3px;
  border-radius: var(--r-sm);
}

.skip-link {
  position: absolute;
  left: var(--sp-4);
  top: -100px;
  z-index: 100;
  padding: var(--sp-2) var(--sp-4);
  background: var(--focus);
  color: #14140a;
  font-weight: 700;
  border-radius: var(--r-md);
  transition: top 150ms ease;
}
.skip-link:focus { top: var(--sp-4); }

.visually-hidden {
  position: absolute !important;
  width: 1px; height: 1px;
  margin: -1px; padding: 0;
  overflow: hidden;
  clip: rect(0 0 0 0);
  clip-path: inset(50%);
  white-space: nowrap;
  border: 0;
}

/* ---------------------------------------------------------------- header */

.site-header {
  border-bottom: 1px solid var(--line);
  padding: var(--sp-4) 0;
}
.site-header .container {
  display: flex;
  align-items: center;
  justify-content: space-between;
  gap: var(--sp-4);
  flex-wrap: wrap;
}
.brand {
  display: flex;
  align-items: center;
  gap: var(--sp-2);
  font-family: var(--mono);
  font-size: 15px;
  font-weight: 700;
  letter-spacing: 0.04em;
  color: var(--text);
  text-decoration: none;
}
.brand .dot {
  width: 10px; height: 10px;
  border-radius: 50%;
  background: linear-gradient(135deg, var(--cyan), var(--magenta));
  flex: none;
}
.site-nav {
  display: flex;
  align-items: center;
  gap: var(--sp-5);
  font-size: 14px;
}
.site-nav a { color: var(--muted); text-decoration: none; }
.site-nav a:hover { color: var(--text); text-decoration: underline; }

/* ------------------------------------------------------------------ hero */

.hero { padding: var(--sp-7) 0 var(--sp-6); }

h1 {
  font-size: clamp(30px, 5.2vw, 46px);
  line-height: 1.12;
  margin: 0 0 var(--sp-4);
  letter-spacing: -0.02em;
  font-weight: 800;
}
h1 .accent {
  background: linear-gradient(100deg, var(--cyan), var(--magenta));
  -webkit-background-clip: text;
  background-clip: text;
  color: transparent;
}

.lede {
  max-width: 700px;
  margin: 0;
  color: var(--muted);
  font-size: 17px;
}

/* ------------------------------------------------------------------ game */

.game {
  display: grid;
  grid-template-columns: minmax(0, 1fr) 268px;
  gap: var(--sp-5);
  align-items: start;
  margin: var(--sp-6) 0 var(--sp-7);
}

@media (max-width: 900px) {
  .game { grid-template-columns: minmax(0, 1fr); }
}

/* aspect-ratio reserves the square before the canvas is sized => no layout shift */
.board-wrap {
  position: relative;
  aspect-ratio: 1 / 1;
  width: 100%;
  max-width: 620px;
  margin: 0 auto;
  border: 1px solid var(--line);
  border-radius: var(--r-lg);
  background: var(--bg);
  overflow: hidden;
  touch-action: none;
}
.board-wrap.has-phase { border-color: rgba(185, 140, 255, 0.55); }
.board-wrap.is-over { border-color: rgba(255, 92, 240, 0.45); }

#board {
  display: block;
  width: 100%;
  height: 100%;
}
#board:focus-visible { outline-offset: -3px; }

.overlay {
  position: absolute;
  inset: 0;
  display: flex;
  flex-direction: column;
  align-items: center;
  justify-content: center;
  gap: var(--sp-3);
  padding: var(--sp-5);
  text-align: center;
  background: rgba(10, 10, 18, 0.88);
  backdrop-filter: blur(2px);
}
.overlay[hidden] { display: none; }
.overlay h2 {
  margin: 0;
  font-family: var(--mono);
  font-size: clamp(22px, 4vw, 30px);
  letter-spacing: 0.02em;
}
.overlay p {
  margin: 0;
  max-width: 34ch;
  color: var(--muted);
  font-size: 15px;
}

/* The tap-to-start target: deliberately large so it works as a mobile overlay. */
.btn-start {
  margin-top: var(--sp-2);
  padding: var(--sp-4) var(--sp-6);
  min-height: 56px;
  font-family: var(--mono);
  font-size: 17px;
  font-weight: 700;
  letter-spacing: 0.05em;
  color: #06060c;
  background: linear-gradient(100deg, var(--cyan), var(--magenta));
  border: 0;
  border-radius: var(--r-md);
  cursor: pointer;
}
.btn-start:hover { filter: brightness(1.08); }

/* ------------------------------------------------------------------- hud */

.panel {
  background: var(--surface);
  border: 1px solid var(--line);
  border-radius: var(--r-lg);
  padding: var(--sp-5);
}
.panel + .panel { margin-top: var(--sp-4); }
.panel h2 {
  margin: 0 0 var(--sp-4);
  font-family: var(--mono);
  font-size: 13px;
  font-weight: 700;
  letter-spacing: 0.12em;
  text-transform: uppercase;
  color: var(--dim);
}

.hud {
  display: grid;
  grid-template-columns: repeat(3, minmax(0, 1fr));
  gap: var(--sp-3);
  font-family: var(--mono);
}
.hud-cell { min-width: 0; }
.hud-label {
  display: block;
  font-size: 11px;
  letter-spacing: 0.1em;
  text-transform: uppercase;
  color: var(--dim);
}
.hud-value {
  display: block;
  font-size: 26px;
  font-weight: 700;
  line-height: 1.2;
  font-variant-numeric: tabular-nums;
  overflow: hidden;
  text-overflow: ellipsis;
  white-space: nowrap;
}
#hud-mult { color: var(--cyan); }
#hud-mult.is-hot { color: var(--magenta); }
#hud-level[hidden] { display: none; }

.combo-track {
  margin-top: var(--sp-3);
  height: 4px;
  border-radius: 999px;
  background: var(--line-soft);
  overflow: hidden;
}
.combo-bar {
  height: 100%;
  transform-origin: left center;
  transform: scaleX(0);
  background: linear-gradient(90deg, var(--cyan), var(--magenta));
}

.phase-flag {
  margin-top: var(--sp-3);
  font-family: var(--mono);
  font-size: 12px;
  letter-spacing: 0.06em;
  color: var(--violet);
}
.phase-flag[hidden] { display: none; }

/* --------------------------------------------------------------- controls */

.modes {
  display: flex;
  flex-direction: column;
  gap: var(--sp-2);
  border: 0;
  margin: 0;
  padding: 0;
}
.modes legend {
  padding: 0;
  margin-bottom: var(--sp-3);
  font-family: var(--mono);
  font-size: 13px;
  font-weight: 700;
  letter-spacing: 0.12em;
  text-transform: uppercase;
  color: var(--dim);
}
.mode-option {
  display: flex;
  align-items: flex-start;
  gap: var(--sp-3);
  padding: var(--sp-3);
  border: 1px solid var(--line);
  border-radius: var(--r-md);
  cursor: pointer;
  background: var(--surface-2);
}
.mode-option:hover { border-color: rgba(62, 233, 245, 0.4); }
.mode-option input { margin: 3px 0 0; flex: none; accent-color: #3ee9f5; }
.mode-option:has(input:checked) { border-color: var(--cyan); }
.mode-option:has(input:focus-visible) {
  outline: 3px solid var(--focus);
  outline-offset: 2px;
}
.mode-name {
  display: block;
  font-family: var(--mono);
  font-size: 14px;
  font-weight: 700;
}
.mode-desc {
  display: block;
  font-size: 12px;
  color: var(--muted);
  line-height: 1.45;
}

.actions {
  display: flex;
  gap: var(--sp-2);
  flex-wrap: wrap;
  margin-top: var(--sp-4);
}
.btn {
  display: inline-flex;
  align-items: center;
  gap: var(--sp-2);
  width: auto;
  flex: none;
  min-height: 44px;
  padding: var(--sp-2) var(--sp-4);
  font-family: var(--mono);
  font-size: 13px;
  font-weight: 700;
  letter-spacing: 0.04em;
  color: var(--text);
  background: var(--surface-2);
  border: 1px solid var(--line);
  border-radius: var(--r-md);
  cursor: pointer;
}
.btn:hover:not(:disabled) { border-color: var(--cyan); color: var(--text); }
.btn:disabled { opacity: 0.45; cursor: not-allowed; }
.btn .icon { font-size: 15px; line-height: 1; }

/* -------------------------------------------------------------- runs table */

.runs { width: 100%; border-collapse: collapse; font-family: var(--mono); font-size: 13px; }
.runs th, .runs td {
  text-align: left;
  padding: var(--sp-2) var(--sp-2) var(--sp-2) 0;
  border-bottom: 1px solid var(--line-soft);
}
.runs thead th {
  font-size: 11px;
  letter-spacing: 0.08em;
  text-transform: uppercase;
  color: var(--dim);
  font-weight: 600;
}
.runs tbody th { font-weight: 600; color: var(--text); }
.runs td { color: var(--muted); font-variant-numeric: tabular-nums; }
.runs-empty { margin: 0; font-size: 13px; color: var(--muted); }
.runs-empty[hidden] { display: none; }

/* --------------------------------------------------------------- articles */

.prose { max-width: 700px; }
.prose h2 {
  font-size: 26px;
  line-height: 1.25;
  margin: var(--sp-7) 0 var(--sp-4);
  letter-spacing: -0.01em;
}
.prose h3 {
  font-size: 18px;
  line-height: 1.35;
  margin: var(--sp-5) 0 var(--sp-2);
  color: var(--text);
}
.prose p { margin: 0 0 var(--sp-4); color: var(--muted); }
.prose ol, .prose ul { margin: 0 0 var(--sp-4); padding-left: var(--sp-5); color: var(--muted); }
.prose li { margin-bottom: var(--sp-2); }
.prose li::marker { color: var(--cyan); }
.prose strong { color: var(--text); font-weight: 600; }
.prose code {
  font-family: var(--mono);
  font-size: 0.9em;
  padding: 1px 5px;
  border-radius: var(--r-sm);
  background: var(--surface-2);
  color: var(--cyan);
}

.section-divider { border: 0; border-top: 1px solid var(--line); margin: var(--sp-7) 0 0; }

.build-note {
  max-width: 700px;
  margin-top: var(--sp-5);
  padding: var(--sp-5);
  background: var(--surface);
  border: 1px solid var(--line);
  border-left: 3px solid var(--cyan);
  border-radius: var(--r-md);
}
.build-note p { margin: 0; color: var(--muted); font-size: 15px; }

/* ---------------------------------------------------------------- footer */

.site-footer {
  margin-top: var(--sp-7);
  padding: var(--sp-6) 0 var(--sp-7);
  border-top: 1px solid var(--line);
  color: var(--muted);
  font-size: 14px;
}
.site-footer p { margin: 0 0 var(--sp-3); max-width: 700px; }
.footer-links { display: flex; gap: var(--sp-4); flex-wrap: wrap; font-size: 13px; }
.footer-links a { color: var(--muted); }

/* --------------------------------------------------------- reduced motion */

@media (prefers-reduced-motion: reduce) {
  *, *::before, *::after {
    animation-duration: 0.001ms !important;
    animation-iteration-count: 1 !important;
    transition-duration: 0.001ms !important;
    scroll-behavior: auto !important;
  }
}