/* ==========================================================================
   SUDOKU — STYLES
   --------------------------------------------------------------------------
   1.  Reset & Base
   2.  Design Tokens (color, type, spacing)
   3.  Layout — Page Shell
   4.  Masthead
   5.  Status Row
   6.  Board
   7.  Cell States (given / user / selected / peer / error / solved)
   8.  Numpad
   9.  Toolbar & Buttons
   10. Helper Text & Colophon
   11. Animations
   12. Responsive
   13. Accessibility (focus, reduced motion)
   ========================================================================== */


/* 1. Reset & Base
   ========================================================================== */
*, *::before, *::after { box-sizing: border-box; }

html, body {
  margin: 0;
  padding: 0;
}

body {
  background: var(--color-paper);
  color: var(--color-ink);
  font-family: var(--font-body);
  -webkit-font-smoothing: antialiased;
}

button, select {
  font-family: inherit;
}


/* 2. Design Tokens
   ========================================================================== */
:root {

  /* Color */
  --color-paper:        #FBF8F2;
  --color-paper-dim:    #F2EDE3;
  --color-ink:          #1F2421;
  --color-ink-soft:     #5B5F5A;
  --color-rule:         #D4CFC4;
  --color-rule-strong:  #B9B2A3;
  --color-given:        #C2410C;   /* burnt orange — fixed/given digits */
  --color-given-dim:    #C2410C1a;
  --color-user:         #1F2421;   /* near-black — user-entered digits */
  --color-accent:       #2D6E5E;   /* deep teal — solve / generate actions */
  --color-accent-dim:   #2D6E5E14;
  --color-error:        #B3261E;
  --color-error-dim:    #B3261E12;
 --color-selected:     #F5E1A4;
--color-peer:         #FBF0D9;

  /* Type */
  --font-display: 'Source Serif 4', Georgia, serif;
  --font-body:    'Source Serif 4', Georgia, serif;
  --font-mono:    'JetBrains Mono', 'SF Mono', Consolas, monospace;

  /* Spacing scale */
  --space-1: 0.25rem;
  --space-2: 0.5rem;
  --space-3: 0.75rem;
  --space-4: 1rem;
  --space-5: 1.5rem;
  --space-6: 2rem;
  --space-7: 3rem;
  --space-8: 4.5rem;

  /* Board sizing */
  --board-size: min(86vw, 460px);
  --cell-size: calc(var(--board-size) / 9);
}


/* 3. Layout — Page Shell
   ========================================================================== */
.page {
  max-width: 620px;
  margin: 0 auto;
  padding: var(--space-7) var(--space-5) var(--space-8);
  display: flex;
  flex-direction: column;
  align-items: center;
}


/* 4. Masthead
   ========================================================================== */
.masthead {
  text-align: center;
  margin-bottom: var(--space-7);
  max-width: 460px;
}

.eyebrow {
  font-family: var(--font-mono);
  font-size: 0.7rem;
  letter-spacing: 0.12em;
  text-transform: uppercase;
  color: var(--color-given);
  margin: 0 0 var(--space-3);
  font-weight: 500;
}

.title {
  font-family: var(--font-display);
  font-weight: 700;
  font-size: clamp(2.75rem, 8vw, 3.75rem);
  line-height: 1;
  margin: 0 0 var(--space-4);
  letter-spacing: -0.01em;
}

.subtitle {
  font-size: 1rem;
  line-height: 1.55;
  color: var(--color-ink-soft);
  margin: 0;
}


/* 5. Status Row
   ========================================================================== */
.puzzle-block {
  width: 100%;
  display: flex;
  flex-direction: column;
  align-items: center;
}

.status-row {
  width: var(--board-size);
  display: flex;
  justify-content: space-between;
  align-items: baseline;
  margin-bottom: var(--space-3);
  padding: 0 var(--space-1);
}

.status-left, .status-right {
  display: flex;
  align-items: baseline;
  gap: var(--space-2);
}

.status-label {
  font-family: var(--font-mono);
  font-size: 0.65rem;
  letter-spacing: 0.08em;
  text-transform: uppercase;
  color: var(--color-ink-soft);
}

.status-value {
  font-family: var(--font-mono);
  font-size: 0.8rem;
  font-weight: 600;
  color: var(--color-ink);
}

.status-value--success { color: var(--color-accent); }
.status-value--error { color: var(--color-error); }


/* 6. Board
   ========================================================================== */
.board-wrap {
  position: relative;
  margin-bottom: var(--space-5);
}

.board {
  display: grid;
  grid-template-columns: repeat(9, var(--cell-size));
  grid-template-rows: repeat(9, var(--cell-size));
  background: var(--color-ink);
  border: 2px solid var(--color-ink);
}

.cell {
  background: var(--color-paper);
  display: flex;
  align-items: center;
  justify-content: center;
  font-family: var(--font-mono);
  font-size: calc(var(--cell-size) * 0.46);
  font-weight: 500;
  color: var(--color-user);
  cursor: pointer;
  position: relative;
  border: 0.5px solid var(--color-rule);
  user-select: none;
  transition: background-color 0.12s ease;
}

/* Thick borders every 3 cells to mark the 3x3 boxes */
.cell[data-col="0"] { border-left: 2px solid var(--color-ink); }
.cell[data-col="2"], .cell[data-col="5"] { border-right: 1.5px solid var(--color-ink); }
.cell[data-col="8"] { border-right: 2px solid var(--color-ink); }
.cell[data-row="0"] { border-top: 2px solid var(--color-ink); }
.cell[data-row="2"], .cell[data-row="5"] { border-bottom: 1.5px solid var(--color-ink); }
.cell[data-row="8"] { border-bottom: 2px solid var(--color-ink); }


/* 7. Cell States
   ========================================================================== */
.cell--given {
  color: var(--color-given);
  font-weight: 600;
  cursor: default;
}

.cell--user {
  color: var(--color-user);
}

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

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

.cell--error {
  background: var(--color-error-dim);
  color: var(--color-error);
}

.cell--solved {
  color: var(--color-accent);
}

.cell--hint {
  color: var(--color-accent);
  font-weight: 600;
}

.cell:not(.cell--given):hover {
  background: var(--color-paper-dim);
}


/* 8. Numpad
   ========================================================================== */
.numpad {
  display: grid;
  grid-template-columns: repeat(10, 1fr);
  gap: var(--space-2);
  width: var(--board-size);
  margin-bottom: var(--space-6);
}

.num-btn {
  aspect-ratio: 1;
  border: 1px solid var(--color-rule-strong);
  background: var(--color-paper);
  color: var(--color-ink);
  font-family: var(--font-mono);
  font-size: 0.95rem;
  font-weight: 500;
  border-radius: 3px;
  cursor: pointer;
  transition: background-color 0.12s ease, border-color 0.12s ease;
}

.num-btn:hover {
  background: var(--color-accent-dim);
  border-color: var(--color-accent);
}

.num-btn--erase {
  font-family: var(--font-display);
  font-size: 1.1rem;
  color: var(--color-ink-soft);
}


/* 9. Toolbar & Buttons
   ========================================================================== */
.toolbar {
  width: 100%;
  max-width: 460px;
  display: flex;
  flex-direction: column;
  gap: var(--space-4);
  margin-bottom: var(--space-5);
}

.toolbar-group {
  display: flex;
  align-items: center;
  gap: var(--space-2);
  flex-wrap: wrap;
  justify-content: center;
}

.toolbar-group[hidden] {
  display: none;
}

.toolbar-label {
  font-family: var(--font-mono);
  font-size: 0.7rem;
  letter-spacing: 0.06em;
  text-transform: uppercase;
  color: var(--color-ink-soft);
  margin-right: var(--space-1);
}

.select-wrap select {
  border: 1px solid var(--color-rule-strong);
  background: var(--color-paper);
  color: var(--color-ink);
  padding: var(--space-2) var(--space-3);
  border-radius: 3px;
  font-size: 0.85rem;
  cursor: pointer;
}

.btn {
  font-family: var(--font-body);
  font-size: 0.9rem;
  font-weight: 600;
  padding: var(--space-2) var(--space-4);
  border-radius: 3px;
  border: 1px solid var(--color-rule-strong);
  background: var(--color-paper);
  color: var(--color-ink);
  cursor: pointer;
  transition: background-color 0.12s ease, border-color 0.12s ease, color 0.12s ease, transform 0.08s ease;
}

.btn:hover {
  background: var(--color-paper-dim);
}

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

.btn--primary {
  background: var(--color-ink);
  border-color: var(--color-ink);
  color: var(--color-paper);
}

.btn--primary:hover {
  background: #34403a;
}

.btn--accent {
  background: var(--color-accent);
  border-color: var(--color-accent);
  color: var(--color-paper);
}

.btn--accent:hover {
  background: #255a4d;
}

.btn--ghost {
  background: transparent;
  border-color: transparent;
  color: var(--color-ink-soft);
}

.btn--ghost:hover {
  background: var(--color-rule);
  color: var(--color-ink);
}

.btn:disabled {
  opacity: 0.4;
  cursor: not-allowed;
  transform: none;
}


/* 10. Helper Text & Colophon
   ========================================================================== */
.hint-text {
  font-size: 0.85rem;
  color: var(--color-ink-soft);
  text-align: center;
  max-width: 420px;
  line-height: 1.5;
  min-height: 2.6em;
  margin: 0;
}
.about-block {
  width: 100%;
  max-width: 460px;
  margin-top: var(--space-7);
  padding-top: var(--space-5);
  border-top: 1px solid var(--color-rule);
}

.about-heading {
  font-family: var(--font-display);
  font-size: 1.1rem;
  font-weight: 700;
  margin: var(--space-5) 0 var(--space-2);
}

.about-heading:first-child {
  margin-top: 0;
}

.about-text {
  font-size: 0.92rem;
  line-height: 1.6;
  color: var(--color-ink-soft);
  margin: 0 0 var(--space-3);
}

.about-text strong {
  color: var(--color-ink);
}
.colophon {
  margin-top: var(--space-8);
  padding-top: var(--space-5);
  border-top: 1px solid var(--color-rule);
  width: 100%;
  max-width: 460px;
  text-align: center;
}

.colophon p {
  font-family: var(--font-mono);
  font-size: 0.7rem;
  color: var(--color-ink-soft);
  letter-spacing: 0.02em;
}


/* 11. Animations
   ========================================================================== */
@keyframes cellFillIn {
  from {
    opacity: 0;
    transform: scale(0.6);
  }
  to {
    opacity: 1;
    transform: scale(1);
  }
}

.cell--fill-anim {
  animation: cellFillIn 0.28s cubic-bezier(0.34, 1.56, 0.64, 1) both;
}

@keyframes shake {
  10%, 90% { transform: translateX(-1px); }
  20%, 80% { transform: translateX(2px); }
  30%, 50%, 70% { transform: translateX(-3px); }
  40%, 60% { transform: translateX(3px); }
}

.board--shake {
  animation: shake 0.4s ease;
}


/* 12. Responsive
   ========================================================================== */
@media (max-width: 480px) {
  .page {
    padding: var(--space-6) var(--space-4) var(--space-7);
  }

  .toolbar-group {
    width: 100%;
  }

  .toolbar-group .btn,
  .toolbar-group .select-wrap,
  .toolbar-group select {
    flex: 1 1 auto;
  }
}


/* 13. Accessibility
   ========================================================================== */
.cell:focus-visible,
.num-btn:focus-visible,
.btn:focus-visible,
select:focus-visible {
  outline: 2px solid var(--color-accent);
  outline-offset: 2px;
  z-index: 1;
}

@media (prefers-reduced-motion: reduce) {
  .cell--fill-anim {
    animation: none;
  }
  .board--shake {
    animation: none;
  }
  .btn {
    transition: none;
  }
}