/* Sudoku — modern, mobile-first */

@import url('https://fonts.googleapis.com/css2?family=Inter:wght@400;500;600;700&family=JetBrains+Mono:wght@500;700&display=swap');

* {
  box-sizing: border-box;
}

:root {
  --bg: #0f172a;
  --bg-2: #1e293b;
  --surface: #ffffff;
  --surface-2: #f8fafc;

  --ink: #0f172a;
  --ink-soft: #334155;
  --ink-muted: #64748b;
  --line: #cbd5e1;
  --line-bold: #0f172a;

  --given: #0f172a;
  --user: #1d4ed8;
  --note: #64748b;

  --sel: #fde68a;
  --peer: #f1f5f9;
  --same: #fcd34d;
  --conflict: #fecaca;
  --wrong: #ef4444;

  --accent: #6366f1;
  --accent-2: #8b5cf6;

  /* Cell size is set by JS-free CSS clamp: fits both width and height. */
  --board-max-w: min(96vw, 540px);
  --cell-size: calc(var(--board-max-w) / 9);
}

html,
body {
  margin: 0;
  padding: 0;
  height: 100%;
  background: var(--bg);
  color: var(--ink);
  font-family: 'Inter', -apple-system, BlinkMacSystemFont, 'Segoe UI', Roboto, sans-serif;
  -webkit-font-smoothing: antialiased;
  /* Allow vertical scrolling when the page is taller than the viewport. */
  overflow-y: auto;
}

body {
  background: radial-gradient(1200px 600px at 50% -10%, #312e81 0%, #0f172a 60%, #020617 100%);
  min-height: 100dvh;
  padding: max(8px, env(safe-area-inset-top)) 8px max(8px, env(safe-area-inset-bottom));
  display: flex;
  justify-content: center;
}

.page {
  display: flex;
  flex-direction: column;
  align-items: center;
  gap: 10px;
  width: 100%;
  max-width: 600px;
}

/* Header */
.page-header {
  display: flex;
  flex-direction: column;
  align-items: center;
  gap: 6px;
  color: white;
}

.page-header h1 {
  margin: 0;
  font-size: clamp(1.25rem, 4vw, 1.75rem);
  font-weight: 700;
  letter-spacing: -0.01em;
}

.badges {
  display: flex;
  gap: 8px;
  flex-wrap: wrap;
  justify-content: center;
}

.badge {
  background: rgba(255, 255, 255, 0.1);
  border: 1px solid rgba(255, 255, 255, 0.15);
  border-radius: 999px;
  padding: 3px 10px;
  font-size: 0.75rem;
  color: white;
  letter-spacing: 0.02em;
}

/* Toolbar */
.toolbar {
  display: flex;
  flex-wrap: wrap;
  gap: 6px;
  justify-content: center;
}

.btn {
  background: rgba(255, 255, 255, 0.08);
  color: white;
  border: 1px solid rgba(255, 255, 255, 0.12);
  padding: 8px 12px;
  border-radius: 10px;
  font-family: inherit;
  font-size: 0.9rem;
  font-weight: 500;
  cursor: pointer;
  transition: all 0.15s ease;
  min-height: 38px;
  display: inline-flex;
  align-items: center;
  gap: 6px;
}

.btn:hover {
  background: rgba(255, 255, 255, 0.15);
}

.btn:active {
  transform: translateY(1px);
}

.btn.primary {
  background: linear-gradient(135deg, var(--accent), var(--accent-2));
  border-color: transparent;
  box-shadow: 0 4px 12px rgba(99, 102, 241, 0.35);
}

.btn.primary:hover {
  filter: brightness(1.1);
}

.icon-btn {
  padding: 8px;
  min-width: 38px;
  justify-content: center;
}

/* Status */
.status-bar {
  display: flex;
  gap: 14px;
  justify-content: center;
  color: white;
}

.stat {
  display: flex;
  flex-direction: column;
  align-items: center;
  gap: 2px;
  min-width: 56px;
}

.stat-label {
  font-size: 0.7rem;
  color: rgba(255, 255, 255, 0.6);
  text-transform: uppercase;
  letter-spacing: 0.05em;
}

.stat-value {
  font-family: 'JetBrains Mono', monospace;
  font-size: 1.25rem;
  font-weight: 700;
  color: white;
}

/* Board */
.board-wrap {
  position: relative;
  background: var(--surface);
  padding: 6px;
  border-radius: 12px;
  box-shadow: 0 20px 60px rgba(0, 0, 0, 0.4), 0 0 0 1px rgba(255, 255, 255, 0.05);
}

.board {
  position: relative;
  display: grid;
  grid-template-columns: repeat(9, var(--cell-size));
  grid-template-rows: repeat(9, var(--cell-size));
  width: calc(var(--cell-size) * 9);
  height: calc(var(--cell-size) * 9);
  background: var(--surface);
  border: 2px solid var(--line-bold);
  border-radius: 6px;
  overflow: hidden;
  touch-action: manipulation;
}

.board.generating {
  pointer-events: none;
  opacity: 0.6;
}

/* X-Sudoku diagonals — drawn as an SVG overlay ABOVE cells so they
   stay visible even when cells have backgrounds (jigsaw tint, peer,
   etc). Pointer events disabled so clicks still hit the cells. */
.x-diagonals {
  position: absolute;
  inset: 0;
  width: 100%;
  height: 100%;
  pointer-events: none;
  z-index: 3;
  overflow: visible;
}

.x-line {
  stroke-width: 0.55;
  vector-effect: non-scaling-stroke;
  /* The SVG is stretched non-uniformly; non-scaling-stroke keeps the
     line width constant regardless of the board's pixel size. */
  stroke-linecap: round;
}

.x-line-main {
  stroke: #6366f1;
  opacity: 0.55;
}

.x-line-anti {
  stroke: #ec4899;
  opacity: 0.55;
}

/* Hyper / windoku — background tint sits behind cells, the dashed
   outline overlay sits above them. Together they make the 4 extra
   regions readable in every variant combo. */
.hyper-region {
  background: rgba(99, 102, 241, 0.2);
  pointer-events: none;
  z-index: 0;
}

.hyper-region-outline {
  pointer-events: none;
  z-index: 2;
  margin: 2px;
  border: 2px dashed rgba(67, 56, 202, 0.85);
  border-radius: 5px;
}

/* Cells */
.cell {
  position: relative;
  z-index: 1;
  background: transparent;
  border-right: 1px solid var(--line);
  border-bottom: 1px solid var(--line);
  display: flex;
  align-items: center;
  justify-content: center;
  cursor: pointer;
  user-select: none;
  font-family: 'Inter', sans-serif;
  font-weight: 500;
  transition: background 0.08s ease;
}

.cell.thick-right {
  border-right: 3px solid var(--line-bold);
}

.cell.thick-bottom {
  border-bottom: 3px solid var(--line-bold);
}

/* Jigsaw region color hint — clear per-region pastel so the regions
   are immediately distinguishable, but still light enough to read
   text on. */
.cell.jigsaw {
  background: hsl(var(--region-hue, 0deg) 70% 87%);
}

.cell:hover:not(.given) {
  background: var(--peer);
}

.cell.jigsaw:hover:not(.given) {
  background: hsl(var(--region-hue, 0deg) 70% 78%);
}

.cell.peer {
  background: var(--peer);
}

.cell.jigsaw.peer {
  background: hsl(var(--region-hue, 0deg) 70% 80%);
}

.cell.same-digit {
  background: var(--same) !important;
}

.cell.selected {
  background: var(--sel) !important;
  box-shadow: inset 0 0 0 3px #f59e0b;
}

.cell.conflict {
  background: var(--conflict) !important;
}

.cell.wrong .cell-value {
  color: var(--wrong);
}

.cell-value {
  font-size: calc(var(--cell-size) * 0.55);
  line-height: 1;
  color: var(--user);
}

.cell.given .cell-value {
  color: var(--given);
  font-weight: 700;
}

.cell-notes {
  display: grid;
  grid-template-columns: repeat(3, 1fr);
  grid-template-rows: repeat(3, 1fr);
  width: 100%;
  height: 100%;
  padding: 1px;
}

.cell-notes .note {
  font-size: calc(var(--cell-size) * 0.22);
  color: var(--note);
  display: flex;
  align-items: center;
  justify-content: center;
  line-height: 1;
}

/* Pause overlay */
.pause-overlay {
  position: absolute;
  inset: 0;
  display: none;
  align-items: center;
  justify-content: center;
  background: rgba(15, 23, 42, 0.94);
  color: white;
  border-radius: 12px;
  cursor: pointer;
}

.pause-overlay.active {
  display: flex;
}

.pause-message {
  text-align: center;
}

.pause-icon {
  font-size: 4rem;
}

/* Message line */
.message {
  min-height: 24px;
  color: rgba(255, 255, 255, 0.85);
  font-size: 0.95rem;
  text-align: center;
}

.message.won {
  color: #fde047;
  font-weight: 700;
  font-size: 1.05rem;
  animation: pop 0.4s ease;
}

@keyframes pop {
  0% {
    transform: scale(0.9);
    opacity: 0;
  }
  100% {
    transform: scale(1);
    opacity: 1;
  }
}

/* Number pad */
.numpad {
  display: grid;
  grid-template-columns: repeat(10, 1fr);
  gap: 4px;
  width: 100%;
  max-width: 540px;
}

.numpad-btn {
  position: relative;
  background: rgba(255, 255, 255, 0.95);
  color: var(--ink);
  border: none;
  border-radius: 8px;
  padding: 0;
  font-family: 'Inter', sans-serif;
  font-size: clamp(1.1rem, 4.5vw, 1.5rem);
  font-weight: 600;
  cursor: pointer;
  transition: all 0.12s ease;
  aspect-ratio: 1 / 1;
  display: flex;
  align-items: center;
  justify-content: center;
  box-shadow: 0 2px 0 rgba(0, 0, 0, 0.15);
}

.numpad-btn:hover {
  background: white;
  transform: translateY(-1px);
}

.numpad-btn:active {
  transform: translateY(1px);
  box-shadow: 0 0 0 rgba(0, 0, 0, 0);
}

.numpad-btn.done {
  background: rgba(255, 255, 255, 0.25);
  color: rgba(255, 255, 255, 0.4);
  box-shadow: none;
}

.numpad-btn.selected-digit {
  background: var(--same);
  color: var(--ink);
}

.numpad-btn.numpad-erase {
  background: rgba(239, 68, 68, 0.85);
  color: white;
  font-size: clamp(1rem, 4vw, 1.25rem);
}

.numpad-btn::after {
  content: attr(data-remaining);
  position: absolute;
  top: 2px;
  right: 4px;
  font-size: 0.6rem;
  font-weight: 500;
  color: var(--ink-muted);
  font-family: 'JetBrains Mono', monospace;
}

.numpad-btn.numpad-erase::after,
.numpad-btn.done::after {
  content: '';
}

/* Settings row */
.settings-row {
  display: flex;
  flex-wrap: wrap;
  gap: 6px;
  justify-content: center;
}

.toggle {
  display: inline-flex;
  align-items: center;
  gap: 6px;
  background: rgba(255, 255, 255, 0.08);
  color: rgba(255, 255, 255, 0.85);
  border: 1px solid rgba(255, 255, 255, 0.12);
  border-radius: 999px;
  padding: 8px 14px;
  font-family: inherit;
  font-size: 0.85rem;
  font-weight: 500;
  cursor: pointer;
  transition: all 0.15s ease;
  min-height: 36px;
}

.toggle:hover {
  background: rgba(255, 255, 255, 0.15);
}

.toggle.is-on {
  background: linear-gradient(135deg, var(--accent), var(--accent-2));
  border-color: transparent;
  color: white;
  box-shadow: 0 0 0 2px rgba(99, 102, 241, 0.3);
}

.toggle-icon {
  font-size: 1rem;
}

.kbd {
  font-family: 'JetBrains Mono', monospace;
  font-size: 0.7rem;
  background: rgba(0, 0, 0, 0.25);
  padding: 2px 6px;
  border-radius: 4px;
  border: 1px solid rgba(255, 255, 255, 0.1);
  margin-left: 2px;
}

/* Help line */
.help {
  display: flex;
  flex-wrap: wrap;
  gap: 8px;
  justify-content: center;
  align-items: center;
  color: rgba(255, 255, 255, 0.55);
  font-size: 0.8rem;
}

.help .sep {
  opacity: 0.4;
}

/* Modal */
.modal {
  display: none;
  position: fixed;
  inset: 0;
  background: rgba(0, 0, 0, 0.7);
  z-index: 100;
  align-items: center;
  justify-content: center;
  padding: 16px;
}

.modal.active {
  display: flex;
}

.modal-content {
  background: var(--surface);
  border-radius: 16px;
  max-width: 460px;
  width: 100%;
  max-height: 90vh;
  overflow-y: auto;
  box-shadow: 0 25px 60px rgba(0, 0, 0, 0.5);
}

.modal-header {
  display: flex;
  justify-content: space-between;
  align-items: center;
  padding: 16px 20px;
  border-bottom: 1px solid var(--line);
}

.modal-header h2 {
  margin: 0;
  font-size: 1.15rem;
  font-weight: 700;
}

.modal-close {
  background: transparent;
  border: none;
  width: 32px;
  height: 32px;
  border-radius: 8px;
  font-size: 1.5rem;
  cursor: pointer;
  color: var(--ink-muted);
}

.modal-close:hover {
  background: var(--surface-2);
  color: var(--ink);
}

.modal-body {
  padding: 20px;
  display: flex;
  flex-direction: column;
  gap: 18px;
}

.field-group {
  border: 1px solid var(--line);
  border-radius: 12px;
  padding: 14px;
  margin: 0;
}

.field-group legend {
  font-weight: 700;
  font-size: 0.85rem;
  text-transform: uppercase;
  letter-spacing: 0.05em;
  color: var(--ink-muted);
  padding: 0 6px;
}

.field-hint {
  margin: 0 0 10px 0;
  font-size: 0.8rem;
  color: var(--ink-muted);
}

.radio-group,
.check-group {
  display: flex;
  flex-wrap: wrap;
  gap: 8px;
}

.radio-pill input,
.check-pill input {
  position: absolute;
  opacity: 0;
  pointer-events: none;
}

.radio-pill {
  display: inline-flex;
  align-items: center;
  background: var(--surface-2);
  border: 1px solid var(--line);
  border-radius: 999px;
  padding: 8px 14px;
  cursor: pointer;
  font-size: 0.9rem;
  font-weight: 500;
  flex: 1 1 auto;
  text-align: center;
  justify-content: center;
  transition: all 0.15s ease;
}

.radio-pill:has(input:checked) {
  background: linear-gradient(135deg, var(--accent), var(--accent-2));
  color: white;
  border-color: transparent;
}

.check-group {
  flex-direction: column;
}

.check-pill {
  display: flex;
  flex-direction: column;
  background: var(--surface-2);
  border: 2px solid var(--line);
  border-radius: 12px;
  padding: 12px 14px;
  cursor: pointer;
  transition: all 0.15s ease;
}

.check-pill:hover {
  background: var(--surface);
}

.check-pill:has(input:checked) {
  background: rgba(99, 102, 241, 0.08);
  border-color: var(--accent);
  box-shadow: 0 0 0 3px rgba(99, 102, 241, 0.12);
}

.check-pill-title {
  font-weight: 700;
  font-size: 0.95rem;
}

.check-pill-sub {
  font-size: 0.78rem;
  color: var(--ink-muted);
  margin-top: 2px;
}

.form-buttons {
  display: flex;
  gap: 8px;
  justify-content: flex-end;
}

.form-buttons .btn {
  background: var(--surface-2);
  color: var(--ink);
  border-color: var(--line);
  min-height: 42px;
  padding: 8px 18px;
}

.form-buttons .btn:hover {
  background: white;
}

.form-buttons .btn.primary {
  background: linear-gradient(135deg, var(--accent), var(--accent-2));
  color: white;
  border-color: transparent;
}

/* Mobile tuning */
@media (max-width: 480px) {
  :root {
    --board-max-w: min(100vw - 16px, 420px);
  }

  .toolbar {
    gap: 4px;
  }

  .btn {
    padding: 6px 10px;
    font-size: 0.8rem;
    min-height: 36px;
  }

  .icon-btn {
    padding: 6px;
    min-width: 36px;
  }

  .stat-value {
    font-size: 1.05rem;
  }

  .help {
    font-size: 0.72rem;
  }

  .check-pill {
    padding: 10px 12px;
  }
}

/* Tall portrait phones: shrink the numpad font so it stays one row. */
@media (max-width: 380px) {
  .numpad-btn {
    font-size: 0.95rem;
  }
}

/* Landscape mobile / short screens: side-by-side board + numpad */
@media (max-height: 640px) and (orientation: landscape) {
  :root {
    --board-max-w: min(70vw, 420px);
  }

  .page {
    flex-direction: row;
    flex-wrap: wrap;
    max-width: none;
    justify-content: center;
    align-items: flex-start;
  }

  .page-header,
  .toolbar,
  .status-bar,
  .settings-row,
  .help,
  .message {
    flex-basis: 100%;
  }

  .numpad {
    grid-template-columns: repeat(2, 1fr);
    width: auto;
    max-width: none;
    margin-left: 12px;
  }

  .numpad-btn {
    aspect-ratio: auto;
    height: calc(var(--cell-size) * 0.95);
    width: calc(var(--cell-size) * 1.2);
  }
}