:root {
  --bg: #0a0d12;
  --bg-elevated: #11151c;
  --bg-card: #141922;
  --border: #1f2630;
  --border-strong: #2a3340;

  --fg: #e6ecf3;
  --fg-muted: #8b96a5;
  --fg-dim: #566271;

  --accent: #00e5a0;
  --accent-dim: #00b37d;
  --accent-glow: rgba(0, 229, 160, 0.18);

  --red: #ff5a5f;
  --red-glow: rgba(255, 90, 95, 0.15);
  --amber: #ffb84d;
  --blue: #5ca2ff;

  --font-ui: 'Geist', 'Helvetica Neue', Helvetica, Arial, sans-serif;
  --font-mono: 'JetBrains Mono', ui-monospace, Menlo, monospace;

  /* clue gutters (estimates used in the cell-size budget) */
  --gut-w: 3.2rem;
  --gut-h: 3.2rem;
  --cell: min(
    calc((100vw - 2rem - var(--gut-w) - 16px) / 8),
    calc((100vh - 252px - var(--gut-h)) / 8),
    46px
  );
}

@supports (height: 1dvh) {
  :root {
    --cell: min(
      calc((100vw - 2rem - var(--gut-w) - 16px) / 8),
      calc((100dvh - 252px - var(--gut-h)) / 8),
      46px
    );
  }
}

* { margin: 0; padding: 0; box-sizing: border-box; }

html, body {
  width: 100%;
  min-height: 100%;
  background: var(--bg);
  color: var(--fg);
  font-family: var(--font-ui);
  overflow: hidden;
  -webkit-user-select: none;
  user-select: none;
}

body {
  display: grid;
  grid-template-rows: auto auto 1fr;
  height: 100vh;
  position: relative;
}
@supports (height: 1dvh) {
  body { height: 100dvh; }
}

body::before {
  content: '';
  position: fixed;
  inset: 0;
  background:
    radial-gradient(ellipse 60% 40% at 50% 0%, var(--accent-glow), transparent 70%),
    linear-gradient(to bottom, rgba(17, 21, 28, 0.5), transparent 40%);
  pointer-events: none;
  z-index: 0;
}

body::after {
  content: '';
  position: fixed;
  inset: 0;
  background-image:
    linear-gradient(to right, var(--border) 1px, transparent 1px),
    linear-gradient(to bottom, var(--border) 1px, transparent 1px);
  background-size: 80px 80px;
  opacity: 0.15;
  pointer-events: none;
  z-index: 0;
}

/* ------------------------------------------------------------
   Topbar
   ------------------------------------------------------------ */
.topbar {
  display: flex;
  align-items: center;
  justify-content: space-between;
  gap: 0.75rem;
  padding: 1rem 1.5rem;
  border-bottom: 1px solid var(--border);
  background: rgba(10, 13, 18, 0.6);
  backdrop-filter: blur(12px);
  -webkit-backdrop-filter: blur(12px);
  position: relative;
  z-index: 10;
}

.back {
  font-family: var(--font-mono);
  font-size: 0.8rem;
  padding: 0.5rem 0.85rem;
  color: var(--fg-muted);
  text-decoration: none;
  border: 1px solid var(--border);
  border-radius: 4px;
  transition: all 0.2s ease;
  white-space: nowrap;
}
.back:hover { color: var(--accent); border-color: var(--accent); }

.title {
  font-family: var(--font-mono);
  font-size: 0.9rem;
  font-weight: 600;
  letter-spacing: 0.18em;
  color: var(--fg);
  white-space: nowrap;
}
.title .sub { color: var(--fg-dim); font-weight: 400; }

/* ------------------------------------------------------------
   HUD
   ------------------------------------------------------------ */
.hud {
  display: flex;
  align-items: center;
  justify-content: space-between;
  gap: 0.6rem 0.75rem;
  padding: 0.7rem 1.5rem;
  background: var(--bg-elevated);
  border-bottom: 1px solid var(--border);
  position: relative;
  z-index: 5;
  flex-wrap: wrap;
}

.hud-stats {
  display: flex;
  align-items: baseline;
  gap: 1.5rem;
}
.hud-stat {
  display: flex;
  align-items: baseline;
  gap: 0.55rem;
}
.hud-label {
  font-family: var(--font-mono);
  font-size: 0.66rem;
  letter-spacing: 0.14em;
  color: var(--fg-dim);
}
.hud-value {
  font-family: var(--font-mono);
  font-size: 1.35rem;
  font-weight: 600;
  color: var(--fg);
  line-height: 1;
  letter-spacing: -0.02em;
  font-variant-numeric: tabular-nums;
}
.hud-best { font-size: 0.95rem; color: var(--accent); }

.hud-tools {
  display: inline-flex;
  border: 1px solid var(--border-strong);
  border-radius: 4px;
  overflow: hidden;
}
.tool-btn {
  font-family: var(--font-mono);
  font-size: 0.68rem;
  font-weight: 500;
  letter-spacing: 0.1em;
  color: var(--fg-muted);
  background: transparent;
  border: none;
  padding: 0.5rem 0.9rem;
  cursor: pointer;
  transition: all 0.2s ease;
  white-space: nowrap;
}
.tool-btn + .tool-btn { border-left: 1px solid var(--border-strong); }
.tool-btn:hover { color: var(--fg); }
.tool-btn[aria-pressed="true"] {
  color: var(--accent);
  background: var(--accent-glow);
  font-weight: 600;
}
.tool-btn:focus-visible {
  outline: 2px solid var(--accent);
  outline-offset: -2px;
}

.hud-actions {
  display: flex;
  gap: 0.5rem;
}
.hud-btn {
  font-family: var(--font-mono);
  font-size: 0.68rem;
  font-weight: 500;
  letter-spacing: 0.1em;
  color: var(--fg-muted);
  background: transparent;
  border: 1px solid var(--border-strong);
  border-radius: 4px;
  padding: 0.5rem 0.8rem;
  cursor: pointer;
  transition: all 0.2s ease;
  white-space: nowrap;
}
.hud-btn:hover:not(:disabled) { color: var(--accent); border-color: var(--accent); }
.hud-btn:disabled { opacity: 0.35; cursor: not-allowed; }

/* ------------------------------------------------------------
   Stage / puzzle
   ------------------------------------------------------------ */
.stage {
  display: flex;
  flex-direction: column;
  align-items: center;
  justify-content: center;
  gap: 0.7rem;
  padding: 1rem;
  position: relative;
  z-index: 2;
  overflow: hidden;
}

.puzzle {
  display: grid;
  grid-template-columns: auto auto;
  grid-template-rows: auto auto;
  column-gap: 7px;
  row-gap: 6px;
}

/* Puzzle stays hidden until START — no pre-studying the clues */
body.prestart .puzzle { visibility: hidden; }

.corner { grid-area: 1 / 1; }

/* Column clues: one stack per column, bottom-aligned */
.cclues {
  grid-area: 1 / 2;
  display: grid;
  grid-template-columns: repeat(8, var(--cell));
  gap: 1px;
  padding: 0 1px; /* mirrors the board border so columns align */
  align-items: end;
}
.cclue {
  display: flex;
  flex-direction: column;
  justify-content: flex-end;
  align-items: center;
  gap: 2px;
  min-height: var(--gut-h);
  font-family: var(--font-mono);
  font-size: clamp(0.55rem, calc(var(--cell) * 0.32), 0.8rem);
  font-weight: 500;
  line-height: 1;
  color: var(--fg-muted);
  transition: color 0.25s ease;
}

/* Row clues: right-aligned, numbers separated by spaces */
.rclues {
  grid-area: 2 / 1;
  display: grid;
  grid-template-rows: repeat(8, var(--cell));
  gap: 1px;
  padding: 1px 0;
  justify-self: end;
}
.rclue {
  display: flex;
  align-items: center;
  justify-content: flex-end;
  font-family: var(--font-mono);
  font-size: clamp(0.55rem, calc(var(--cell) * 0.32), 0.8rem);
  font-weight: 500;
  line-height: 1;
  color: var(--fg-muted);
  white-space: nowrap;
  transition: color 0.25s ease;
}

/* Satisfied clue lines fade back into the stone */
.cclue.done, .rclue.done { color: var(--fg-dim); }

/* Board */
.board {
  grid-area: 2 / 2;
  display: grid;
  grid-template-columns: repeat(8, var(--cell));
  grid-template-rows: repeat(8, var(--cell));
  gap: 1px;
  background: var(--border);
  border: 1px solid var(--border-strong);
  border-radius: 6px;
  overflow: hidden;
  touch-action: none;
}

.cell {
  position: relative;
  background: var(--bg-card);
  border: none;
  padding: 0;
  cursor: pointer;
  touch-action: none;
  -webkit-tap-highlight-color: transparent;
}
.cell:not(.fill):not(.mark):hover { background: #1a212d; }
.cell:focus-visible {
  outline: 2px solid var(--accent);
  outline-offset: -2px;
  z-index: 2;
}

/* Laid tessera: warm stone tile with an inset gap and stable
   per-cell brightness jitter (--h / --l set inline, seeded by index) */
.cell.fill::after {
  content: '';
  position: absolute;
  inset: 1.5px;
  border-radius: 2px;
  background: hsl(var(--h, 38), 40%, calc(var(--l, 50) * 1%));
  box-shadow:
    inset 0 1px 0 rgba(255, 255, 255, 0.14),
    inset 0 -1px 0 rgba(0, 0, 0, 0.28);
}

/* Mark: a small dim ×, purely a note */
.cell.mark::after {
  content: '×';
  position: absolute;
  inset: 0;
  display: flex;
  align-items: center;
  justify-content: center;
  font-family: var(--font-mono);
  font-size: calc(var(--cell) * 0.42);
  font-weight: 500;
  line-height: 1;
  color: var(--fg-dim);
}

/* Win reveal: the restored floor warms up with a per-cell hue
   jitter, sweeping diagonally (--h2 / --d set inline per cell) */
.board.won .cell { cursor: default; }
.board.won .cell.fill::after {
  background: hsl(var(--h2, 36), 52%, calc((var(--l, 50) + 5) * 1%));
  box-shadow:
    inset 0 1px 0 rgba(255, 255, 255, 0.2),
    inset 0 -1px 0 rgba(0, 0, 0, 0.28),
    0 0 8px rgba(255, 184, 77, 0.12);
  transition: background 0.55s ease var(--d, 0ms), box-shadow 0.55s ease var(--d, 0ms);
}
.board.won .cell.mark::after { opacity: 0; transition: opacity 0.45s ease; }

/* status line */
.status {
  font-family: var(--font-mono);
  font-size: 0.68rem;
  letter-spacing: 0.12em;
  color: var(--fg-dim);
  min-height: 1.1em;
  text-align: center;
}

/* ------------------------------------------------------------
   Overlays (start / end)
   ------------------------------------------------------------ */
.overlay {
  position: fixed;
  inset: 0;
  z-index: 100;
  display: flex;
  align-items: center;
  justify-content: center;
  padding: 1.5rem;
  background: rgba(10, 13, 18, 0.85);
  backdrop-filter: blur(8px);
  -webkit-backdrop-filter: blur(8px);
  animation: fadeIn 0.3s ease-out;
  overflow-y: auto;
}
.overlay[hidden] { display: none; }
@keyframes fadeIn { from { opacity: 0; } }

.overlay-inner {
  max-width: 560px;
  width: 100%;
  text-align: center;
  background: var(--bg-card);
  border: 1px solid var(--border-strong);
  border-radius: 10px;
  padding: 2.5rem 2rem;
  margin: auto;
}

.overlay .eyebrow {
  font-family: var(--font-mono);
  font-size: 0.72rem;
  letter-spacing: 0.18em;
  color: var(--accent);
  margin-bottom: 1rem;
}
.overlay h1 {
  font-family: var(--font-mono);
  font-size: clamp(1.5rem, 4vw, 2.2rem);
  font-weight: 600;
  color: var(--fg);
  line-height: 1.1;
  margin-bottom: 1rem;
  letter-spacing: -0.02em;
}
.overlay h1 .accent { color: var(--accent); }
.overlay .lede {
  color: var(--fg-muted);
  font-size: 0.95rem;
  line-height: 1.55;
  margin-bottom: 1.4rem;
}

.rules {
  list-style: none;
  text-align: left;
  margin: 0 auto 1.5rem;
  max-width: 460px;
  display: flex;
  flex-direction: column;
  gap: 0.55rem;
}
.rules li {
  display: flex;
  align-items: baseline;
  gap: 0.75rem;
  color: var(--fg-muted);
  font-size: 0.85rem;
  line-height: 1.45;
}
.rule-mark {
  flex: 0 0 auto;
  font-family: var(--font-mono);
  font-size: 0.68rem;
  font-weight: 600;
  letter-spacing: 0.05em;
  color: var(--amber);
  border: 1px solid var(--border-strong);
  border-radius: 3px;
  padding: 2px 6px;
  min-width: 3.4em;
  text-align: center;
}

.keys {
  display: flex;
  justify-content: center;
  gap: 1.25rem;
  margin-bottom: 1.75rem;
  flex-wrap: wrap;
}
.key-group {
  font-family: var(--font-mono);
  font-size: 0.72rem;
  color: var(--fg-muted);
  letter-spacing: 0.08em;
  display: flex;
  align-items: center;
  gap: 0.4rem;
}
.kbd {
  display: inline-block;
  min-width: 1.8em;
  padding: 2px 6px;
  border: 1px solid var(--border-strong);
  border-bottom-width: 2px;
  border-radius: 3px;
  color: var(--accent);
  font-weight: 600;
  text-align: center;
  font-family: var(--font-mono);
}

.primary {
  background: var(--accent);
  color: var(--bg);
  font-family: var(--font-mono);
  font-weight: 600;
  font-size: 0.9rem;
  letter-spacing: 0.1em;
  padding: 0.9rem 2.2rem;
  border: none;
  border-radius: 4px;
  cursor: pointer;
  transition: all 0.2s ease;
}
.primary:hover {
  background: var(--fg);
  transform: translateY(-1px);
}

.overlay-cta {
  display: flex;
  align-items: center;
  justify-content: center;
  gap: 0.75rem;
  flex-wrap: wrap;
  margin-top: 1.5rem;
}
.ghost {
  background: transparent;
  color: var(--fg-muted);
  font-family: var(--font-mono);
  font-weight: 500;
  font-size: 0.85rem;
  letter-spacing: 0.08em;
  padding: 0.9rem 1.4rem;
  border: 1px solid var(--border-strong);
  border-radius: 4px;
  cursor: pointer;
  text-decoration: none;
  transition: all 0.2s ease;
  display: inline-block;
}
.ghost:hover {
  color: var(--fg);
  border-color: var(--fg-muted);
}

.pb-tag {
  display: inline-block;
  font-family: var(--font-mono);
  font-size: 0.65rem;
  font-weight: 600;
  letter-spacing: 0.14em;
  color: var(--bg);
  background: var(--accent);
  border-radius: 3px;
  padding: 0.25rem 0.6rem;
  margin-bottom: 0.25rem;
}
.pb-tag[hidden] { display: none; }

/* ------------------------------------------------------------
   Responsive
   ------------------------------------------------------------ */
@media (max-width: 640px) {
  .topbar { padding: 0.75rem 1rem; }
  .title { font-size: 0.75rem; letter-spacing: 0.12em; }
  .title .sub { display: none; }

  .hud { padding: 0.55rem 1rem; }
  .hud-stats { gap: 1rem; }
  .hud-value { font-size: 1.15rem; }
  .hud-best { font-size: 0.85rem; }
  .hud-btn { padding: 0.45rem 0.55rem; font-size: 0.62rem; }
  .tool-btn { padding: 0.45rem 0.7rem; font-size: 0.62rem; }

  .overlay-inner { padding: 1.75rem 1.25rem; }
  .rules li { font-size: 0.8rem; }
  .keys { gap: 0.75rem; }
}

@media (prefers-reduced-motion: reduce) {
  * { animation: none !important; transition: none !important; }
}