body.sudoku-page {
  --sudoku-ink: #17242d;
  --sudoku-muted: #51616c;
  --sudoku-paper: #f7f4ee;
  --sudoku-panel: #ffffff;
  --sudoku-line: #6f7a82;
  --sudoku-heavy-line: #1f2b33;
  --sudoku-accent: #c84d2b;
  --sudoku-accent-dark: #99371f;
  --sudoku-focus: #f8d35a;
  --sudoku-soft: #eaf3f1;
  --sudoku-error: #ffd9d6;
  --sudoku-error-line: #cf3f33;
  margin: 0;
  min-height: 100vh;
  background: linear-gradient(180deg, #f7f4ee 0%, #eaf3f1 100%);
  color: var(--sudoku-ink);
  font-family: system-ui, -apple-system, BlinkMacSystemFont, "Hiragino Sans", "Yu Gothic", sans-serif;
}

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

.sudoku-page button,
.sudoku-page a {
  font: inherit;
}

.sudoku-page button {
  color: inherit;
  touch-action: manipulation;
}

.sudoku-app {
  width: min(980px, 100%);
  margin: 0 auto;
  padding: max(14px, env(safe-area-inset-top)) 14px max(22px, env(safe-area-inset-bottom));
}

.sudoku-header {
  display: grid;
  grid-template-columns: auto 1fr auto;
  align-items: center;
  gap: 10px;
  margin-bottom: 12px;
}

.sudoku-common-actions {
  display: grid;
  grid-template-columns: repeat(3, 1fr);
  gap: 8px;
  margin-bottom: 12px;
}

.sudoku-back-link,
.sudoku-level-badge {
  min-height: 44px;
  display: inline-flex;
  align-items: center;
  justify-content: center;
  border: 2px solid var(--sudoku-heavy-line);
  border-radius: 8px;
  background: var(--sudoku-panel);
  color: var(--sudoku-ink);
  padding: 8px 10px;
  text-decoration: none;
  font-size: 0.95rem;
  font-weight: 800;
  white-space: nowrap;
}

.sudoku-title-block {
  min-width: 0;
}

.sudoku-kicker {
  margin: 0 0 2px;
  color: var(--sudoku-accent-dark);
  font-size: 0.92rem;
  font-weight: 900;
}

.sudoku-page h1,
.sudoku-page h2 {
  margin: 0;
  letter-spacing: 0;
  line-height: 1.18;
}

.sudoku-page h1 {
  font-size: clamp(1.45rem, 6vw, 2.35rem);
}

.sudoku-page h2 {
  font-size: 1.25rem;
}

.sudoku-start-panel,
.sudoku-status,
.sudoku-controls {
  border: 2px solid #d5d0c6;
  border-radius: 8px;
  background: var(--sudoku-panel);
  padding: 12px;
}

.sudoku-start-panel {
  display: grid;
  gap: 10px;
  margin-bottom: 12px;
}

.sudoku-start-panel p {
  margin: 6px 0 0;
  color: var(--sudoku-muted);
  font-size: 1rem;
  line-height: 1.55;
}

.sudoku-level-buttons {
  display: grid;
  grid-template-columns: repeat(3, 1fr);
  gap: 8px;
}

.sudoku-status {
  display: grid;
  grid-template-columns: 1fr auto;
  align-items: center;
  gap: 12px;
  margin-bottom: 12px;
}

.sudoku-status-title,
.sudoku-message {
  margin: 0;
}

.sudoku-status-title {
  font-size: 1.08rem;
  font-weight: 900;
}

.sudoku-message {
  color: var(--sudoku-muted);
  font-size: 1rem;
  line-height: 1.5;
}

.sudoku-message.is-error {
  color: var(--sudoku-error-line);
  font-weight: 900;
}

.sudoku-stats {
  display: grid;
  gap: 6px;
  min-width: 126px;
  font-weight: 900;
  text-align: right;
}

.sudoku-board-section {
  display: grid;
  place-items: center;
  margin-bottom: 12px;
}

.sudoku-board-wrap {
  width: min(100%, 640px);
}

.sudoku-board {
  display: grid;
  grid-template-columns: repeat(9, 1fr);
  width: 100%;
  aspect-ratio: 1;
  border: 3px solid var(--sudoku-heavy-line);
  background: var(--sudoku-heavy-line);
}

.sudoku-cell {
  display: grid;
  place-items: center;
  width: 100%;
  min-width: 0;
  border: 1px solid var(--sudoku-line);
  background: #fffdf8;
  color: var(--sudoku-ink);
  font-size: clamp(1.25rem, 7vw, 2.45rem);
  font-weight: 900;
  line-height: 1;
  cursor: pointer;
  -webkit-tap-highlight-color: transparent;
}

.sudoku-cell:nth-child(3n) {
  border-right-width: 3px;
  border-right-color: var(--sudoku-heavy-line);
}

.sudoku-cell:nth-child(9n) {
  border-right-width: 1px;
  border-right-color: var(--sudoku-line);
}

.sudoku-cell:nth-child(n + 19):nth-child(-n + 27),
.sudoku-cell:nth-child(n + 46):nth-child(-n + 54) {
  border-bottom-width: 3px;
  border-bottom-color: var(--sudoku-heavy-line);
}

.sudoku-cell.is-fixed {
  background: #e9edf0;
  color: #101820;
}

.sudoku-cell.is-selected {
  background: var(--sudoku-focus);
  outline: 4px solid var(--sudoku-accent);
  outline-offset: -4px;
}

.sudoku-cell.is-related {
  background: #fff3c7;
}

.sudoku-cell.is-same-number {
  background: #dceee9;
}

.sudoku-cell.is-error {
  background: var(--sudoku-error);
  color: #8d241d;
}

.sudoku-cell.is-fixed.is-error {
  background: #f3c4bf;
}

.sudoku-controls {
  display: grid;
  gap: 10px;
}

.sudoku-number-pad {
  display: grid;
  grid-template-columns: repeat(9, 1fr);
  gap: 6px;
}

.sudoku-actions {
  display: grid;
  grid-template-columns: repeat(3, 1fr);
  gap: 8px;
}

.sudoku-primary,
.sudoku-secondary,
.sudoku-number-button,
.sudoku-text-button {
  min-height: 52px;
  border-radius: 8px;
  border: 2px solid var(--sudoku-heavy-line);
  padding: 8px 10px;
  font-weight: 900;
}

.sudoku-primary {
  background: var(--sudoku-accent);
  color: #ffffff;
}

.sudoku-secondary,
.sudoku-number-button,
.sudoku-text-button {
  background: #ffffff;
  color: var(--sudoku-ink);
}

.sudoku-number-button {
  min-height: 48px;
  padding: 6px;
  font-size: 1.35rem;
}

.sudoku-text-button {
  border-color: #b7c1c7;
  color: var(--sudoku-muted);
}

.sudoku-wide {
  width: 100%;
}

.sudoku-modal {
  position: fixed;
  inset: 0;
  z-index: 20;
  display: grid;
  place-items: center;
  padding: 18px;
  background: rgba(23, 36, 45, 0.58);
}

.sudoku-modal[hidden] {
  display: none;
}

.sudoku-modal-box {
  display: grid;
  gap: 12px;
  width: min(420px, 100%);
  border: 3px solid var(--sudoku-heavy-line);
  border-radius: 8px;
  background: var(--sudoku-panel);
  padding: 18px;
}

.sudoku-result-list {
  display: grid;
  grid-template-columns: 1fr 1fr;
  gap: 8px;
  margin: 0;
}

.sudoku-result-list div {
  border: 2px solid #d5d0c6;
  border-radius: 8px;
  padding: 10px;
  background: var(--sudoku-paper);
}

.sudoku-result-list dt {
  color: var(--sudoku-muted);
  font-size: 0.92rem;
  font-weight: 800;
}

.sudoku-result-list dd {
  margin: 4px 0 0;
  font-size: 1.25rem;
  font-weight: 900;
}

.sudoku-clear-message {
  margin: 0;
  color: var(--sudoku-muted);
  line-height: 1.5;
}

@media (orientation: landscape) and (max-height: 620px) {
  .sudoku-app {
    width: min(760px, 100%);
  }

  .sudoku-board-wrap {
    width: min(72vh, 100%);
  }
}

@media (max-width: 720px) {
  .sudoku-header {
    grid-template-columns: 1fr auto;
  }

  .sudoku-back-link {
    grid-column: 1 / -1;
    justify-self: start;
  }

  .sudoku-status {
    grid-template-columns: 1fr;
  }

  .sudoku-stats {
    grid-template-columns: auto auto auto;
    justify-content: space-between;
    text-align: left;
  }
}

@media (max-width: 430px) {
  .sudoku-app {
    padding-left: 10px;
    padding-right: 10px;
  }

  .sudoku-level-buttons,
  .sudoku-actions,
  .sudoku-common-actions {
    grid-template-columns: 1fr;
  }

  .sudoku-number-pad {
    gap: 4px;
  }

  .sudoku-number-button {
    min-height: 44px;
    font-size: 1.2rem;
  }

  .sudoku-cell {
    font-size: clamp(1.05rem, 8vw, 1.75rem);
  }
}