:root {
  --bg: #f6f5f2;
  --surface: #ffffff;
  --text: #1d1f24;
  --muted: #7a7d85;
  --line: #d9d8d3;
  --line-strong: #2b2d33;
  --cage: #6c6f78;
  --accent: #3d63d6;
  --accent-soft: #e3e9fb;
  --peer: #e9ecf2;
  --same: #cfdaf7;
  --selected: #b7c8f5;
  --area: #fde9b8;
  --area-strong: #f6d27a;
  --given: #1d1f24;
  --entered: #3d63d6;
  --error: #d64545;
  --error-soft: #fbe1e1;
  --key: #ffffff;
  --key-hover: #f0f1f4;
  --shadow: 0 1px 2px rgb(0 0 0 / 0.05), 0 4px 16px rgb(0 0 0 / 0.04);
  color-scheme: light;
}

@media (prefers-color-scheme: dark) {
  :root:not([data-theme="light"]) {
    --bg: #121316;
    --surface: #1b1d21;
    --text: #e6e7ea;
    --muted: #8b8f98;
    --line: #2f3238;
    --line-strong: #9a9ea8;
    --cage: #8d919b;
    --accent: #7d9cf0;
    --accent-soft: #232c45;
    --peer: #22252b;
    --same: #2c3a5e;
    --selected: #34477a;
    --area: #4a3d1c;
    --area-strong: #6e5718;
    --given: #e6e7ea;
    --entered: #8eaaf5;
    --error: #f07272;
    --error-soft: #4a2427;
    --key: #1f2227;
    --key-hover: #272a30;
    --shadow: 0 1px 2px rgb(0 0 0 / 0.4);
    color-scheme: dark;
  }
}
:root[data-theme="dark"] {
  --bg: #121316;
  --surface: #1b1d21;
  --text: #e6e7ea;
  --muted: #8b8f98;
  --line: #2f3238;
  --line-strong: #9a9ea8;
  --cage: #8d919b;
  --accent: #7d9cf0;
  --accent-soft: #232c45;
  --peer: #22252b;
  --same: #2c3a5e;
  --selected: #34477a;
  --area: #4a3d1c;
  --area-strong: #6e5718;
  --given: #e6e7ea;
  --entered: #8eaaf5;
  --error: #f07272;
  --error-soft: #4a2427;
  --key: #1f2227;
  --key-hover: #272a30;
  --shadow: 0 1px 2px rgb(0 0 0 / 0.4);
  color-scheme: dark;
}

* { box-sizing: border-box; }
html, body { margin: 0; height: 100%; }
body {
  background: var(--bg);
  color: var(--text);
  font-family: ui-sans-serif, system-ui, -apple-system, "Segoe UI", Roboto, sans-serif;
  -webkit-font-smoothing: antialiased;
  -webkit-tap-highlight-color: transparent;
  overscroll-behavior: none;
}
button { font: inherit; color: inherit; cursor: pointer; }
svg { fill: none; stroke: currentColor; stroke-width: 1.8; stroke-linecap: round; stroke-linejoin: round; }

/* ---------- Layout ---------- */
.app {
  --panel: clamp(260px, 30vw, 340px);
  --gap: clamp(16px, 3vw, 40px);
  --board: min(calc(100dvh - 48px), calc(100vw - var(--panel) - var(--gap) - 48px), 720px);
  min-height: 100dvh;
  display: grid;
  grid-template-columns: var(--board) var(--panel);
  gap: var(--gap);
  align-items: center;
  justify-content: center;
  padding: 24px;
}

@media (orientation: portrait) {
  .app {
    --board: min(calc(100vw - 16px), calc(100dvh - 330px), 640px);
    grid-template-columns: var(--board);
    align-content: start;
    gap: 12px;
    padding: max(8px, env(safe-area-inset-top)) 8px max(12px, env(safe-area-inset-bottom));
  }
  .app .panel { display: contents; }
  .topbar { order: -2; }
  .stats { order: -1; }
  .board-area { order: 0; }
  .tools { order: 1; }
  .keypad { order: 2; }
  .area-hint { order: 3; }
}

/* ---------- Board ---------- */
.board-area { display: flex; justify-content: center; }
.board {
  position: relative;
  width: var(--board);
  aspect-ratio: 1;
  display: grid;
  grid-template-columns: repeat(9, 1fr);
  grid-template-rows: repeat(9, 1fr);
  background: var(--surface);
  border: 2px solid var(--line-strong);
  border-radius: 6px;
  overflow: hidden;
  touch-action: none;
  user-select: none;
  -webkit-user-select: none;
  box-shadow: var(--shadow);
  font-size: calc(var(--board) / 9);
}
.cell {
  position: relative;
  display: grid;
  place-items: center;
  border-right: 1px solid var(--line);
  border-bottom: 1px solid var(--line);
  cursor: pointer;
  transition: background-color 80ms;
}
.cell.c8 { border-right: 0; }
.cell.r8 { border-bottom: 0; }
.cell.c2, .cell.c5 { border-right: 2px solid var(--line-strong); }
.cell.r2, .cell.r5 { border-bottom: 2px solid var(--line-strong); }

.cell.peer { background: var(--peer); }
.cell.same { background: var(--same); }
.cell.area { background: var(--area); }
.cell.area-focus { box-shadow: inset 0 0 0 2px var(--area-strong); }
.cell.conflict { background: var(--error-soft); }
.cell.selected { background: var(--selected); }

.value {
  font-size: 0.56em;
  font-weight: 450;
  line-height: 1;
  color: var(--entered);
  font-variant-numeric: tabular-nums;
}
.cell.given .value { color: var(--given); font-weight: 500; }
.cell.wrong .value { color: var(--error); }
.cell.pop .value { animation: pop 180ms ease-out; }
@keyframes pop { from { transform: scale(0.7); opacity: 0.4; } }

.notes {
  position: absolute;
  inset: 22% 10% 8% 12%;
  display: grid;
  grid-template-columns: repeat(3, 1fr);
  grid-template-rows: repeat(3, 1fr);
  font-size: max(8px, 0.2em);
  line-height: 1;
  color: var(--muted);
  font-variant-numeric: tabular-nums;
}
.notes span { display: grid; place-items: center; }
.notes span.hl { color: var(--accent); font-weight: 700; }

.sum {
  position: absolute;
  top: 3%;
  left: 5%;
  font-size: max(9px, 0.2em);
  font-weight: 600;
  line-height: 1;
  color: var(--cage);
  font-variant-numeric: tabular-nums;
  pointer-events: none;
}

.cages {
  position: absolute;
  inset: 0;
  width: 100%;
  height: 100%;
  pointer-events: none;
  stroke: var(--cage);
  stroke-width: 1;
  stroke-dasharray: 3 2.5;
  stroke-linecap: butt;
  z-index: 1;
}

.pause-cover {
  position: absolute;
  inset: 0;
  z-index: 3;
  background: var(--surface);
  display: grid;
  place-items: center;
}
.pause-cover[hidden] { display: none; }
.resume {
  width: 72px; height: 72px;
  border-radius: 50%;
  border: 0;
  background: var(--accent);
  color: var(--surface);
  display: grid; place-items: center;
}
.resume svg { width: 32px; height: 32px; fill: currentColor; stroke: none; margin-left: 4px; }

/* ---------- Panel ---------- */
.panel { display: flex; flex-direction: column; gap: 20px; }

.topbar { display: flex; align-items: center; justify-content: space-between; }
.brand { margin: 0; font-size: 1.35rem; font-weight: 650; letter-spacing: -0.02em; }
.top-actions { display: flex; gap: 6px; }
.icon-btn {
  width: 40px; height: 40px;
  border-radius: 10px;
  border: 0;
  background: transparent;
  color: var(--muted);
  display: grid; place-items: center;
}
.icon-btn:hover { background: var(--key-hover); color: var(--text); }
.icon-btn svg { width: 22px; height: 22px; }
.i-moon { display: none; }
:root[data-theme="dark"] .i-sun { display: none; }
:root[data-theme="dark"] .i-moon { display: block; }
@media (prefers-color-scheme: dark) {
  :root:not([data-theme="light"]) .i-sun { display: none; }
  :root:not([data-theme="light"]) .i-moon { display: block; }
}

.stats { display: grid; grid-template-columns: repeat(3, 1fr); gap: 8px; }
.stat { display: flex; flex-direction: column; gap: 2px; }
.stat-time { align-items: flex-end; text-align: right; }
.stat-label { font-size: 0.72rem; text-transform: uppercase; letter-spacing: 0.08em; color: var(--muted); }
.stat-value { font-size: 1.05rem; font-weight: 550; font-variant-numeric: tabular-nums; display: flex; align-items: center; gap: 4px; }
.stat-value.danger { color: var(--error); }
.pause-btn {
  border: 0; background: transparent; padding: 2px;
  width: 28px; height: 28px; border-radius: 50%;
  color: var(--muted); display: grid; place-items: center;
}
.pause-btn:hover { background: var(--key-hover); color: var(--text); }
.pause-btn svg { width: 18px; height: 18px; }
.pause-btn .i-play { display: none; fill: currentColor; stroke: none; }
.paused .pause-btn .i-play { display: block; }
.paused .pause-btn .i-pause { display: none; }

.tools { display: grid; grid-template-columns: repeat(4, 1fr); gap: 8px; }
.tool {
  position: relative;
  display: flex; flex-direction: column; align-items: center; gap: 6px;
  padding: 10px 4px;
  border: 0;
  border-radius: 12px;
  background: transparent;
  color: var(--muted);
  font-size: 0.78rem;
}
.tool svg { width: 26px; height: 26px; }
.tool:hover { background: var(--key-hover); color: var(--text); }
.tool:active { transform: scale(0.96); }
.tool[aria-pressed="true"] { color: var(--accent); }
.badge {
  position: absolute; top: 4px; right: calc(50% - 26px);
  font-style: normal; font-size: 0.6rem; font-weight: 700; text-transform: uppercase;
  padding: 1px 5px; border-radius: 6px;
  background: var(--line); color: var(--muted);
}
.tool[aria-pressed="true"] .badge { background: var(--accent); color: var(--surface); }

.keypad { display: grid; grid-template-columns: repeat(3, 1fr); gap: 8px; }
.key {
  position: relative;
  aspect-ratio: 1.15;
  border: 1px solid var(--line);
  border-radius: 12px;
  background: var(--key);
  color: var(--accent);
  font-size: 1.9rem;
  font-weight: 450;
  font-variant-numeric: tabular-nums;
  display: grid; place-items: center;
  transition: background-color 100ms, opacity 100ms, transform 60ms;
  touch-action: manipulation;
}
.key:hover { background: var(--key-hover); }
.key:active { transform: scale(0.95); }
.key small {
  position: absolute; right: 8px; bottom: 5px;
  font-size: 0.68rem; font-weight: 500; color: var(--muted);
}
.key.done { opacity: 0.25; pointer-events: none; }
.notes-mode .key { color: var(--muted); }
/* Area mode: missing digits stand out, present ones recede. */
.area-mode .key { opacity: 0.3; }
.area-mode .key.missing { opacity: 1; background: var(--area); border-color: var(--area-strong); color: var(--text); }

.area-hint { margin: 0; font-size: 0.78rem; color: var(--muted); line-height: 1.4; text-align: center; }

/* ---------- Phone portrait ---------- */
@media (orientation: portrait) {
  .topbar, .stats, .tools, .keypad, .area-hint { width: var(--board); margin: 0 auto; }
  .stats { padding: 0 4px; }
  .tools { gap: 4px; }
  .tool { padding: 6px 2px; }
  .tool svg { width: 24px; height: 24px; }
  .keypad { grid-template-columns: repeat(9, 1fr); gap: 4px; }
  .key { aspect-ratio: 0.72; font-size: clamp(1.4rem, 6.5vw, 2rem); border-radius: 10px; }
  .key { padding-bottom: 10px; }
  .key small { right: 0; left: 0; bottom: 4px; text-align: center; font-size: 0.6rem; }
  .area-hint { font-size: 0.72rem; }
}
/* ---------- Short landscape screens (phones on their side) ---------- */
@media (orientation: landscape) and (max-height: 560px) {
  .app {
    --panel: clamp(240px, 40vw, 340px);
    --board: min(calc(100dvh - 16px), calc(100vw - var(--panel) - var(--gap) - 24px));
    --gap: 16px;
    grid-template-columns: var(--board) var(--panel);
    padding: 8px max(12px, env(safe-area-inset-right)) 8px max(12px, env(safe-area-inset-left));
    align-content: center;
  }
  .app .panel { display: flex; gap: 8px; }
  .brand { font-size: 1.1rem; }
  .icon-btn { width: 32px; height: 32px; }
  .stat-value { font-size: 0.95rem; }
  .tools { gap: 4px; }
  .tool { padding: 4px 2px; flex-direction: row; justify-content: center; font-size: 0.72rem; }
  .tool svg { width: 20px; height: 20px; }
  .badge { display: none; }
  .keypad { gap: 6px; }
  .key { aspect-ratio: auto; height: max(40px, calc((100dvh - 190px) / 3)); font-size: 1.4rem; }
  .area-hint { display: none; }
}

@media (orientation: portrait) and (min-width: 600px) {
  .keypad { gap: 8px; }
}
@media (hover: none) {
  .area-hint .desktop { display: none; }
}

/* ---------- Dialogs ---------- */
.dialog {
  border: 0;
  border-radius: 16px;
  padding: 24px;
  background: var(--surface);
  color: var(--text);
  width: min(340px, calc(100vw - 32px));
  box-shadow: 0 20px 60px rgb(0 0 0 / 0.25);
}
.dialog::backdrop { background: rgb(0 0 0 / 0.35); backdrop-filter: blur(2px); }
.dialog h2 { margin: 0 0 12px; font-size: 1.2rem; font-weight: 650; }
.dialog p { margin: 0 0 20px; color: var(--muted); line-height: 1.5; }
.levels { display: grid; gap: 8px; margin-bottom: 12px; }
.levels button, .end-actions button {
  padding: 12px; border-radius: 10px;
  border: 1px solid var(--line); background: var(--key);
  font-weight: 550;
}
.levels button:hover, .end-actions button:hover { background: var(--key-hover); }
.levels button.current { border-color: var(--accent); color: var(--accent); }
.end-actions { display: grid; grid-template-columns: 1fr 1fr; gap: 8px; }
.end-actions button.primary { background: var(--accent); border-color: var(--accent); color: var(--surface); }
.link { border: 0; background: none; color: var(--muted); width: 100%; padding: 8px; }

.loading {
  position: fixed; left: 50%; bottom: 24px; transform: translateX(-50%);
  display: flex; align-items: center; gap: 10px;
  padding: 10px 16px; border-radius: 999px;
  background: var(--surface); color: var(--muted); box-shadow: var(--shadow);
  font-size: 0.85rem; z-index: 10;
}
.loading[hidden] { display: none; }
.loading span {
  width: 14px; height: 14px; border-radius: 50%;
  border: 2px solid var(--line); border-top-color: var(--accent);
  animation: spin 700ms linear infinite;
}
@keyframes spin { to { transform: rotate(360deg); } }

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