:root {
  --bg: #0f172a;
  --surface: #1e293b;
  --surface-2: #26344b;
  --line: #334155;
  --line-strong: #5b6b84;
  --text: #e2e8f0;
  --muted: #94a3b8;
  --accent: #14b8a6;
  --accent-2: #5eead4;
  --accent-ink: #042f2e;
  --danger: #f87171;
  --radius: 12px;
  --shadow: 0 18px 40px rgb(2 6 23 / 0.5);
  --shadow-sm: 0 2px 8px rgb(2 6 23 / 0.35);
  --t: 180ms ease;
  --gutter: 16px;
  --board: min(calc(100vw - 2 * var(--gutter)), 560px, max(288px, calc(100dvh - 312px)));
  color-scheme: dark;
}

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

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

body {
  margin: 0;
  min-height: 100vh;
  min-height: 100dvh;
  display: flex;
  flex-direction: column;
  background:
    radial-gradient(1200px 520px at 50% -180px, rgb(20 184 166 / 0.13), transparent 70%),
    var(--bg);
  color: var(--text);
  font-family: system-ui, -apple-system, "Segoe UI", Roboto, "Helvetica Neue", Arial, sans-serif;
  line-height: 1.4;
  -webkit-tap-highlight-color: transparent;
}

button,
select {
  font: inherit;
  color: inherit;
}

.sr-only {
  position: absolute;
  width: 1px;
  height: 1px;
  margin: -1px;
  overflow: hidden;
  clip-path: inset(50%);
  white-space: nowrap;
}

.icon {
  width: 20px;
  height: 20px;
  flex: none;
  fill: none;
  stroke: currentColor;
  stroke-width: 2;
  stroke-linecap: round;
  stroke-linejoin: round;
}

/* ---------- Header ---------- */

.topbar {
  width: 100%;
  max-width: 980px;
  margin: 0 auto;
  padding: 8px var(--gutter);
  display: flex;
  align-items: center;
  justify-content: space-between;
  gap: 10px;
}

.brand {
  margin: 0;
  display: flex;
  align-items: center;
  gap: 9px;
  font-size: 20px;
  font-weight: 750;
  letter-spacing: -0.01em;
}

.logo {
  width: 28px;
  height: 28px;
  flex: none;
  filter: drop-shadow(0 3px 10px rgb(20 184 166 / 0.35));
}

.topbar-actions {
  display: flex;
  align-items: center;
  gap: 8px;
}

/* ---------- Buttons ---------- */

.btn {
  min-height: 44px;
  min-width: 44px;
  padding: 0 14px;
  display: inline-flex;
  align-items: center;
  justify-content: center;
  gap: 6px;
  border: 1px solid var(--line);
  border-radius: var(--radius);
  background: var(--surface);
  font-size: 15px;
  font-weight: 600;
  cursor: pointer;
  touch-action: manipulation;
  transition: background-color var(--t), border-color var(--t), transform var(--t), opacity var(--t);
}

.btn:hover {
  background: var(--surface-2);
  border-color: var(--line-strong);
}

.btn:active {
  transform: scale(0.97);
}

.btn-primary {
  background: var(--accent);
  border-color: var(--accent);
  color: var(--accent-ink);
  box-shadow: 0 6px 18px rgb(20 184 166 / 0.25);
}

.btn-primary:hover {
  background: var(--accent-2);
  border-color: var(--accent-2);
}

.btn-restart {
  padding: 0 12px;
}

.btn-lang {
  padding: 0;
  width: 44px;
  font-size: 13px;
  font-weight: 750;
  letter-spacing: 0.04em;
  color: var(--accent-2);
}

:focus-visible {
  outline: 2px solid var(--accent-2);
  outline-offset: 2px;
}

.wide-only {
  display: none;
}

/* ---------- Layout ---------- */

.game {
  flex: 1;
  display: grid;
  grid-template-columns: var(--board);
  grid-template-areas:
    "status"
    "board"
    "actions"
    "pad";
  justify-content: center;
  align-content: start;
  gap: 8px;
  padding: 2px var(--gutter) 10px;
}

.status {
  grid-area: status;
  display: flex;
  align-items: center;
  justify-content: space-between;
  gap: 12px;
  min-height: 40px;
}

.field {
  display: flex;
  align-items: center;
  gap: 8px;
  color: var(--muted);
  font-size: 13px;
  font-weight: 600;
}

select {
  appearance: none;
  height: 40px;
  padding: 0 34px 0 12px;
  border: 1px solid var(--line);
  border-radius: 10px;
  background:
    url("data:image/svg+xml,%3Csvg xmlns='http://www.w3.org/2000/svg' viewBox='0 0 24 24' fill='none' stroke='%2394a3b8' stroke-width='2.5' stroke-linecap='round' stroke-linejoin='round'%3E%3Cpath d='m6 9 6 6 6-6'/%3E%3C/svg%3E")
      no-repeat right 10px center / 16px,
    var(--surface);
  color: var(--text);
  font-size: 15px;
  font-weight: 600;
  cursor: pointer;
  transition: border-color var(--t);
}

select:hover {
  border-color: var(--line-strong);
}

.timer {
  display: flex;
  align-items: center;
  gap: 6px;
  color: var(--text);
  font-size: 19px;
  font-weight: 650;
  font-variant-numeric: tabular-nums;
}

.timer .icon {
  color: var(--accent-2);
}

/* ---------- Board ---------- */

.board-wrap {
  grid-area: board;
}

.board {
  width: var(--board);
  height: var(--board);
  display: grid;
  grid-template-columns: repeat(3, 1fr);
  grid-template-rows: repeat(3, 1fr);
  gap: 3px;
  padding: 3px;
  border-radius: var(--radius);
  background: var(--line-strong);
  box-shadow: var(--shadow);
  touch-action: none;
  user-select: none;
  -webkit-user-select: none;
}

.box {
  display: grid;
  grid-template-columns: repeat(3, 1fr);
  grid-template-rows: repeat(3, 1fr);
  gap: 1px;
  min-width: 0;
  min-height: 0;
  overflow: hidden;
  background: var(--line);
}

.box:nth-child(1) { border-top-left-radius: 9px; }
.box:nth-child(3) { border-top-right-radius: 9px; }
.box:nth-child(7) { border-bottom-left-radius: 9px; }
.box:nth-child(9) { border-bottom-right-radius: 9px; }

.cell {
  position: relative;
  min-width: 0;
  min-height: 0;
  margin: 0;
  padding: 0;
  display: grid;
  place-items: center;
  border: 0;
  border-radius: 0;
  background: var(--surface);
  color: var(--accent-2);
  font-size: calc(var(--board) * 0.058);
  font-weight: 500;
  line-height: 1;
  cursor: pointer;
  transition: background-color var(--t), color var(--t), box-shadow var(--t);
}

/* The selection highlight is the focus indicator for cells. */
.cell:focus {
  outline: none;
}

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

.cell.peer {
  background: color-mix(in srgb, #94a3b8 11%, var(--surface));
}

.cell.same {
  background: color-mix(in srgb, var(--accent) 24%, var(--surface));
}

.cell.conflict,
.cell.mistake {
  color: var(--danger);
}

.cell.conflict:not(.selected),
.cell.mistake:not(.selected) {
  background: color-mix(in srgb, var(--danger) 20%, var(--surface));
}

.cell.conflict.given {
  color: var(--text);
}

.cell.mistake .value {
  text-decoration: line-through;
  text-decoration-thickness: 2px;
}

.cell.selected {
  background: color-mix(in srgb, var(--accent) 40%, var(--surface));
  box-shadow: inset 0 0 0 2px var(--accent-2);
  z-index: 1;
}

.cell.hinted .value {
  animation: hint-pop 700ms ease;
}

.notes {
  position: absolute;
  inset: 7%;
  display: grid;
  grid-template-columns: repeat(3, 1fr);
  grid-template-rows: repeat(3, 1fr);
  place-items: center;
  color: var(--muted);
  font-size: calc(var(--board) * 0.03);
  font-weight: 650;
  pointer-events: none;
}

.notes .match {
  color: var(--accent-2);
}

.cell.selected .notes {
  color: var(--text);
}

.board.won .cell {
  animation: wave 900ms ease var(--wave);
}

@keyframes hint-pop {
  0% { transform: scale(0.4); opacity: 0; }
  60% { transform: scale(1.25); }
  100% { transform: scale(1); opacity: 1; }
}

@keyframes wave {
  0%, 100% { background-color: var(--surface); }
  40% { background-color: color-mix(in srgb, var(--accent) 45%, var(--surface)); }
}

/* ---------- Actions ---------- */

.actions {
  grid-area: actions;
  display: grid;
  grid-template-columns: repeat(5, 1fr);
  gap: 6px;
}

.tool {
  position: relative;
  min-height: 50px;
  padding: 5px 2px;
  display: flex;
  flex-direction: column;
  align-items: center;
  justify-content: center;
  gap: 3px;
  border: 1px solid var(--line);
  border-radius: var(--radius);
  background: var(--surface);
  color: var(--muted);
  font-size: 12px;
  font-weight: 600;
  cursor: pointer;
  touch-action: manipulation;
  transition: background-color var(--t), color var(--t), border-color var(--t), transform var(--t), opacity var(--t);
}

.tool:hover:not(:disabled) {
  background: var(--surface-2);
  color: var(--text);
}

.tool:active:not(:disabled) {
  transform: scale(0.96);
}

.tool:disabled {
  opacity: 0.45;
  cursor: not-allowed;
}

.tool[aria-pressed="true"] {
  background: color-mix(in srgb, var(--accent) 20%, var(--surface));
  border-color: var(--accent);
  color: var(--accent-2);
}

.badge {
  position: absolute;
  top: 4px;
  right: 6px;
  min-width: 18px;
  height: 18px;
  padding: 0 5px;
  display: grid;
  place-items: center;
  border-radius: 9px;
  background: var(--accent);
  color: var(--accent-ink);
  font-size: 11px;
  font-weight: 800;
  line-height: 1;
}

/* ---------- Number pad ---------- */

.pad {
  grid-area: pad;
  display: grid;
  grid-template-columns: repeat(10, 1fr);
  gap: 6px;
}

.pad-btn {
  grid-column: span 2;
  min-height: 46px;
  padding: 2px 0;
  display: flex;
  flex-direction: column;
  align-items: center;
  justify-content: center;
  border: 1px solid var(--line);
  border-radius: var(--radius);
  background: var(--surface);
  color: var(--text);
  cursor: pointer;
  touch-action: manipulation;
  transition: background-color var(--t), border-color var(--t), transform var(--t), opacity var(--t);
}

.pad-btn:nth-child(6) {
  grid-column: 2 / span 2;
}

.pad-btn:hover {
  background: var(--surface-2);
  border-color: var(--line-strong);
}

.pad-btn:active {
  transform: scale(0.95);
}

.pad-digit {
  font-size: 22px;
  font-weight: 650;
  line-height: 1.1;
}

.pad-count {
  color: var(--muted);
  font-size: 11px;
  font-weight: 600;
  font-variant-numeric: tabular-nums;
}

.pad-btn.done {
  opacity: 0.38;
}

.pad.notes-mode .pad-btn {
  border-style: dashed;
  border-color: color-mix(in srgb, var(--accent) 55%, var(--line));
}

.pad.notes-mode .pad-digit {
  color: var(--accent-2);
  font-size: 17px;
}

.keys-help {
  grid-area: help;
  display: none;
  margin: 0;
  color: var(--muted);
  font-size: 13px;
}

/* ---------- Footer & toast ---------- */

.footer {
  padding: 6px var(--gutter) calc(14px + env(safe-area-inset-bottom));
  color: var(--muted);
  font-size: 13px;
  text-align: center;
}

/* A 40px-tall tap target; the negative margins keep the footer's height unchanged. */
.footer a {
  display: inline-block;
  padding: 11px 6px;
  margin: -11px -6px;
  color: var(--accent-2);
  text-decoration: none;
}

.footer a:hover {
  text-decoration: underline;
}

.toast {
  position: fixed;
  left: 50%;
  bottom: calc(24px + env(safe-area-inset-bottom));
  z-index: 10;
  max-width: calc(100vw - 2 * var(--gutter));
  margin: 0;
  padding: 10px 18px;
  border: 1px solid var(--line-strong);
  border-radius: 999px;
  background: #0b1222;
  box-shadow: var(--shadow-sm);
  font-size: 14px;
  font-weight: 600;
  text-align: center;
  opacity: 0;
  transform: translate(-50%, 12px);
  pointer-events: none;
  transition: opacity var(--t), transform var(--t);
}

.toast.show {
  opacity: 1;
  transform: translate(-50%, 0);
}

/* ---------- Dialogs ---------- */

.dialog {
  width: min(380px, calc(100vw - 2 * var(--gutter)));
  padding: 24px;
  border: 1px solid var(--line);
  border-radius: 16px;
  background: var(--surface);
  color: var(--text);
  box-shadow: var(--shadow);
}

.dialog[open] {
  animation: dialog-in 220ms ease;
}

.dialog::backdrop {
  background: rgb(2 6 23 / 0.65);
  backdrop-filter: blur(3px);
}

.dialog h2 {
  margin: 4px 0 6px;
  font-size: 24px;
  text-align: center;
}

.dialog-text {
  margin: 0 0 18px;
  color: var(--muted);
  font-size: 15px;
}

.dialog-win .dialog-text {
  text-align: center;
}

.dialog-actions {
  display: flex;
  justify-content: flex-end;
  gap: 10px;
}

.dialog-win .dialog-actions {
  justify-content: center;
}

.win-icon {
  display: block;
  width: 56px;
  height: 56px;
  margin: 0 auto;
  fill: color-mix(in srgb, var(--accent) 20%, transparent);
  stroke: var(--accent-2);
  stroke-width: 3;
  stroke-linecap: round;
  stroke-linejoin: round;
}

.stats {
  margin: 0 0 20px;
  display: grid;
  grid-template-columns: repeat(3, 1fr);
  gap: 8px;
}

.stats div {
  padding: 10px 6px;
  border-radius: 10px;
  background: var(--bg);
  text-align: center;
}

.stats dt {
  color: var(--muted);
  font-size: 12px;
}

.stats dd {
  margin: 2px 0 0;
  font-size: 18px;
  font-weight: 700;
  font-variant-numeric: tabular-nums;
}

@keyframes dialog-in {
  from { opacity: 0; transform: translateY(10px) scale(0.98); }
  to { opacity: 1; transform: none; }
}

/* ---------- Wider screens ---------- */

@media (min-width: 400px) {
  .topbar-actions {
    gap: 10px;
  }
}

@media (max-width: 379px) {
  .icon-new {
    display: none;
  }
}

@media (min-width: 560px) {
  .wide-only {
    display: inline;
  }

  .btn-restart {
    padding: 0 14px;
  }
}

@media (min-width: 860px) {
  :root {
    --board: min(600px, max(380px, calc(100dvh - 176px)), calc(100vw - 420px));
  }

  .topbar {
    padding-top: 14px;
    padding-bottom: 14px;
  }

  .brand {
    font-size: 23px;
  }

  .game {
    grid-template-columns: var(--board) 300px;
    grid-template-rows: auto auto auto 1fr;
    grid-template-areas:
      "board status"
      "board actions"
      "board pad"
      "board help";
    align-content: center;
    column-gap: 36px;
    row-gap: 14px;
    padding-bottom: 16px;
  }

  .status {
    padding: 12px 16px;
    border: 1px solid var(--line);
    border-radius: var(--radius);
    background: var(--surface);
  }

  .timer {
    font-size: 24px;
  }

  .pad {
    grid-template-columns: repeat(3, 1fr);
    gap: 10px;
  }

  .pad-btn,
  .pad-btn:nth-child(6) {
    grid-column: auto;
    aspect-ratio: 1.12;
  }

  .pad-digit {
    font-size: 30px;
  }

  .pad.notes-mode .pad-digit {
    font-size: 24px;
  }

  .pad-count {
    font-size: 12px;
  }

  .tool {
    min-height: 62px;
  }

  .keys-help {
    display: block;
    align-self: end;
    line-height: 1.6;
  }
}

@media (prefers-reduced-motion: reduce) {
  *,
  *::before,
  *::after {
    animation-duration: 1ms !important;
    animation-delay: 0ms !important;
    animation-iteration-count: 1 !important;
    transition-duration: 1ms !important;
  }
}