/* ===== CSS Variables & Reset ===== */
:root {
  --font-display: 'Unbounded', sans-serif;
  --font-body: 'Golos Text', sans-serif;

  --color-bg: #f0f2f5;
  --color-surface: #ffffff;
  --color-surface-alt: #f7f8fa;
  --color-border: #e2e5ea;
  --color-border-thick: #bcc3ce;
  --color-text: #1a1d23;
  --color-text-secondary: #6b7280;
  --color-text-muted: #9ca3af;

  --color-primary: #4f46e5;
  --color-primary-hover: #4338ca;
  --color-primary-light: #eef2ff;
  --color-primary-glow: rgba(79, 70, 229, 0.15);

  --color-accent: #06b6d4;
  --color-success: #10b981;
  --color-warning: #f59e0b;
  --color-error: #ef4444;
  --color-error-light: #fef2f2;

  --color-cell-selected: #e0e7ff;
  --color-cell-highlight: #f0f4ff;
  --color-cell-same-num: #dbeafe;
  --color-cell-given: var(--color-text);
  --color-cell-user: var(--color-primary);
  --color-cell-error: var(--color-error);
  --color-cell-notes: var(--color-text-secondary);

  --radius-sm: 6px;
  --radius-md: 10px;
  --radius-lg: 16px;
  --radius-xl: 24px;

  --shadow-sm: 0 1px 2px rgba(0, 0, 0, 0.04);
  --shadow-md: 0 4px 12px rgba(0, 0, 0, 0.06);
  --shadow-lg: 0 8px 30px rgba(0, 0, 0, 0.08);
  --shadow-xl: 0 20px 60px rgba(0, 0, 0, 0.1);

  --transition: 0.2s cubic-bezier(0.4, 0, 0.2, 1);

  --board-size: min(480px, calc(100vw - 32px));
  --cell-size: calc(var(--board-size) / 9);
}

[data-theme="dark"] {
  --color-bg: #0f1117;
  --color-surface: #1a1d27;
  --color-surface-alt: #22252f;
  --color-border: #2d3140;
  --color-border-thick: #3d4255;
  --color-text: #e8eaed;
  --color-text-secondary: #9aa0ad;
  --color-text-muted: #6b7280;

  --color-primary: #818cf8;
  --color-primary-hover: #a5b4fc;
  --color-primary-light: rgba(129, 140, 248, 0.12);
  --color-primary-glow: rgba(129, 140, 248, 0.2);

  --color-error-light: rgba(239, 68, 68, 0.12);

  --color-cell-selected: rgba(129, 140, 248, 0.25);
  --color-cell-highlight: rgba(129, 140, 248, 0.08);
  --color-cell-same-num: rgba(129, 140, 248, 0.15);
  --color-cell-user: #a5b4fc;
  --color-cell-notes: var(--color-text-muted);

  --shadow-sm: 0 1px 2px rgba(0, 0, 0, 0.2);
  --shadow-md: 0 4px 12px rgba(0, 0, 0, 0.3);
  --shadow-lg: 0 8px 30px rgba(0, 0, 0, 0.35);
  --shadow-xl: 0 20px 60px rgba(0, 0, 0, 0.4);
}

*, *::before, *::after {
  margin: 0;
  padding: 0;
  box-sizing: border-box;
}

html {
  font-size: 16px;
  -webkit-tap-highlight-color: transparent;
}

body {
  font-family: var(--font-body);
  background: var(--color-bg);
  color: var(--color-text);
  min-height: 100dvh;
  line-height: 1.5;
  overflow-x: hidden;
  transition: background var(--transition), color var(--transition);
}

button {
  font-family: inherit;
  cursor: pointer;
  border: none;
  background: none;
  color: inherit;
  font-size: inherit;
}

/* ===== Layout ===== */
#app {
  display: flex;
  flex-direction: column;
  min-height: 100dvh;
  max-width: 560px;
  margin: 0 auto;
  padding: 0 16px;
}

/* ===== Header ===== */
.header {
  display: flex;
  align-items: center;
  justify-content: space-between;
  padding: 16px 0;
}

.header__logo {
  display: flex;
  align-items: center;
  gap: 10px;
}

.header__icon {
  font-size: 28px;
  color: var(--color-primary);
  line-height: 1;
}

.header__title {
  font-family: var(--font-display);
  font-size: 1.5rem;
  font-weight: 700;
  letter-spacing: -0.02em;
  background: linear-gradient(135deg, var(--color-primary), var(--color-accent));
  -webkit-background-clip: text;
  -webkit-text-fill-color: transparent;
  background-clip: text;
}

/* ===== Buttons ===== */
.btn {
  display: inline-flex;
  align-items: center;
  justify-content: center;
  gap: 6px;
  padding: 8px 18px;
  border-radius: var(--radius-md);
  font-weight: 600;
  font-size: 0.875rem;
  transition: all var(--transition);
  white-space: nowrap;
}

.btn--primary {
  background: var(--color-primary);
  color: #fff;
  box-shadow: 0 2px 8px var(--color-primary-glow);
}

.btn--primary:hover {
  background: var(--color-primary-hover);
  transform: translateY(-1px);
  box-shadow: 0 4px 16px var(--color-primary-glow);
}

.btn--primary:active {
  transform: translateY(0);
}

.btn--ghost {
  padding: 8px;
  border-radius: var(--radius-sm);
  color: var(--color-text-secondary);
}

.btn--ghost:hover {
  background: var(--color-primary-light);
  color: var(--color-primary);
}

.btn--lg {
  padding: 12px 32px;
  font-size: 1rem;
  border-radius: var(--radius-lg);
}

/* ===== Game Bar ===== */
.game-bar {
  display: flex;
  align-items: center;
  justify-content: space-between;
  gap: 12px;
  margin-bottom: 12px;
  flex-wrap: wrap;
}

.difficulty-selector {
  display: flex;
  gap: 4px;
  background: var(--color-surface);
  border-radius: var(--radius-lg);
  padding: 4px;
  box-shadow: var(--shadow-sm);
  border: 1px solid var(--color-border);
}

.difficulty-btn {
  padding: 6px 14px;
  border-radius: var(--radius-md);
  font-size: 0.8125rem;
  font-weight: 500;
  color: var(--color-text-secondary);
  transition: all var(--transition);
}

.difficulty-btn:hover {
  color: var(--color-text);
  background: var(--color-surface-alt);
}

.difficulty-btn.active {
  background: var(--color-primary);
  color: #fff;
  box-shadow: 0 2px 8px var(--color-primary-glow);
}

/* ===== Game Stats ===== */
.game-stats {
  display: flex;
  justify-content: center;
  gap: 32px;
  margin-bottom: 16px;
}

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

.stat__label {
  font-size: 0.75rem;
  font-weight: 500;
  color: var(--color-text-muted);
  text-transform: uppercase;
  letter-spacing: 0.05em;
}

.stat__value {
  font-family: var(--font-display);
  font-size: 1.05rem;
  font-weight: 600;
  color: var(--color-text);
}

#mistakes.error {
  color: var(--color-error);
  animation: shake 0.4s ease;
}

@keyframes shake {
  0%, 100% { transform: translateX(0); }
  25% { transform: translateX(-4px); }
  75% { transform: translateX(4px); }
}

/* ===== Board ===== */
.board-container {
  position: relative;
  display: flex;
  justify-content: center;
  margin-bottom: 20px;
}

.board {
  display: grid;
  grid-template-columns: repeat(9, var(--cell-size));
  grid-template-rows: repeat(9, var(--cell-size));
  background: var(--color-surface);
  border: 2.5px solid var(--color-text);
  border-radius: var(--radius-lg);
  overflow: hidden;
  box-shadow: var(--shadow-lg);
  user-select: none;
  -webkit-user-select: none;
}

.cell {
  position: relative;
  display: flex;
  align-items: center;
  justify-content: center;
  font-family: var(--font-display);
  font-size: calc(var(--cell-size) * 0.45);
  font-weight: 600;
  border: 0.5px solid var(--color-border);
  cursor: pointer;
  transition: background var(--transition);
  background: var(--color-surface);
  color: var(--color-cell-given);
}

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

/* Thick borders for 3x3 boxes */
.cell[data-col="2"], .cell[data-col="5"] {
  border-right: 2px solid var(--color-border-thick);
}
.cell[data-col="3"], .cell[data-col="6"] {
  border-left: 2px solid var(--color-border-thick);
}
.cell[data-row="2"], .cell[data-row="5"] {
  border-bottom: 2px solid var(--color-border-thick);
}
.cell[data-row="3"], .cell[data-row="6"] {
  border-top: 2px solid var(--color-border-thick);
}

/* Cell states */
.cell--selected {
  background: var(--color-cell-selected) !important;
  box-shadow: inset 0 0 0 2px var(--color-primary);
  z-index: 2;
}

.cell--highlighted {
  background: var(--color-cell-highlight) !important;
}

.cell--same-number {
  background: var(--color-cell-same-num) !important;
}

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

.cell--error {
  color: var(--color-cell-error) !important;
  background: var(--color-error-light) !important;
  animation: cellError 0.4s ease;
}

@keyframes cellError {
  0%, 100% { transform: scale(1); }
  50% { transform: scale(1.1); }
}

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

.cell--correct-reveal {
  animation: correctPop 0.4s cubic-bezier(0.34, 1.56, 0.64, 1);
}

@keyframes correctPop {
  0% { transform: scale(0.5); opacity: 0.3; }
  100% { transform: scale(1); opacity: 1; }
}

/* Notes */
.cell__notes {
  position: absolute;
  inset: 1px;
  display: grid;
  grid-template-columns: repeat(3, 1fr);
  grid-template-rows: repeat(3, 1fr);
  pointer-events: none;
}

.cell__note {
  display: flex;
  align-items: center;
  justify-content: center;
  font-size: calc(var(--cell-size) * 0.2);
  font-weight: 500;
  color: var(--color-cell-notes);
  font-family: var(--font-body);
  line-height: 1;
}

/* ===== Start Overlay (pre-game) ===== */
.start-overlay {
  position: absolute;
  inset: 0;
  display: flex;
  align-items: center;
  justify-content: center;
  background: rgba(255, 255, 255, 0.6);
  backdrop-filter: blur(12px);
  -webkit-backdrop-filter: blur(12px);
  border-radius: var(--radius-lg);
  z-index: 8;
  transition: opacity 0.5s ease, visibility 0.5s ease;
}

[data-theme="dark"] .start-overlay {
  background: rgba(15, 17, 23, 0.65);
}

.start-overlay.hidden {
  opacity: 0;
  visibility: hidden;
  pointer-events: none;
}

.start-overlay__content {
  text-align: center;
  padding: 24px;
}

.start-overlay__icon {
  width: 80px;
  height: 80px;
  margin: 0 auto 16px;
  display: flex;
  align-items: center;
  justify-content: center;
  background: var(--color-primary);
  color: #fff;
  border-radius: 50%;
  box-shadow: 0 8px 32px var(--color-primary-glow), 0 0 0 8px rgba(79, 70, 229, 0.08);
  animation: startPulse 2s ease-in-out infinite;
}

[data-theme="dark"] .start-overlay__icon {
  box-shadow: 0 8px 32px var(--color-primary-glow), 0 0 0 8px rgba(129, 140, 248, 0.1);
}

@keyframes startPulse {
  0%, 100% { transform: scale(1); box-shadow: 0 8px 32px var(--color-primary-glow), 0 0 0 8px rgba(79, 70, 229, 0.08); }
  50% { transform: scale(1.05); box-shadow: 0 12px 40px var(--color-primary-glow), 0 0 0 12px rgba(79, 70, 229, 0.12); }
}

.start-overlay__icon svg {
  margin-left: 4px;
}

.start-overlay__title {
  font-family: var(--font-display);
  font-size: 1.4rem;
  font-weight: 700;
  margin-bottom: 6px;
}

.start-overlay__text {
  font-size: 0.85rem;
  color: var(--color-text-secondary);
  max-width: 280px;
  margin: 0 auto 20px;
  line-height: 1.5;
}

.start-overlay__btn {
  padding: 14px 40px;
  font-size: 1.05rem;
}

/* ===== Game Overlay (win/lose) ===== */
.game-overlay {
  position: absolute;
  inset: 0;
  display: flex;
  align-items: center;
  justify-content: center;
  background: rgba(255, 255, 255, 0.92);
  backdrop-filter: blur(8px);
  border-radius: var(--radius-lg);
  opacity: 0;
  pointer-events: none;
  transition: opacity 0.4s ease;
  z-index: 10;
}

[data-theme="dark"] .game-overlay {
  background: rgba(15, 17, 23, 0.92);
}

.game-overlay.visible {
  opacity: 1;
  pointer-events: all;
}

.overlay-content {
  text-align: center;
  padding: 24px;
}

.overlay-icon {
  font-size: 3rem;
  margin-bottom: 12px;
  animation: bounce 0.6s ease infinite alternate;
}

@keyframes bounce {
  from { transform: translateY(0); }
  to { transform: translateY(-8px); }
}

.overlay-title {
  font-family: var(--font-display);
  font-size: 1.5rem;
  font-weight: 700;
  margin-bottom: 4px;
}

.overlay-text {
  color: var(--color-text-secondary);
  margin-bottom: 16px;
}

.overlay-stats {
  display: flex;
  justify-content: center;
  gap: 24px;
  margin-bottom: 20px;
}

.overlay-stat {
  display: flex;
  flex-direction: column;
  align-items: center;
}

.overlay-stat__value {
  font-family: var(--font-display);
  font-size: 1.2rem;
  font-weight: 700;
  color: var(--color-primary);
}

.overlay-stat__label {
  font-size: 0.75rem;
  color: var(--color-text-muted);
}

/* ===== Controls ===== */
.controls {
  display: flex;
  flex-direction: column;
  gap: 16px;
  margin-bottom: 24px;
}

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

.tool-btn {
  display: flex;
  flex-direction: column;
  align-items: center;
  gap: 4px;
  padding: 10px 16px;
  border-radius: var(--radius-md);
  font-size: 0.7rem;
  font-weight: 500;
  color: var(--color-text-secondary);
  transition: all var(--transition);
  position: relative;
}

.tool-btn:hover {
  background: var(--color-surface);
  color: var(--color-primary);
  box-shadow: var(--shadow-sm);
}

.tool-btn.active {
  background: var(--color-primary-light);
  color: var(--color-primary);
}

.tool-btn svg {
  flex-shrink: 0;
}

.hint-count {
  position: absolute;
  top: 4px;
  right: 8px;
  background: var(--color-primary);
  color: #fff;
  font-size: 0.6rem;
  font-weight: 700;
  width: 16px;
  height: 16px;
  border-radius: 50%;
  display: flex;
  align-items: center;
  justify-content: center;
  line-height: 1;
}

/* ===== Number Pad ===== */
.controls__numbers {
  display: flex;
  justify-content: center;
  gap: 6px;
}

.num-btn {
  width: calc(var(--board-size) / 9 - 2px);
  max-width: 52px;
  aspect-ratio: 1;
  display: flex;
  align-items: center;
  justify-content: center;
  font-family: var(--font-display);
  font-size: 1.2rem;
  font-weight: 600;
  border-radius: var(--radius-md);
  background: var(--color-surface);
  border: 1px solid var(--color-border);
  color: var(--color-text);
  transition: all var(--transition);
  box-shadow: var(--shadow-sm);
}

.num-btn:hover {
  background: var(--color-primary-light);
  border-color: var(--color-primary);
  color: var(--color-primary);
  transform: translateY(-2px);
  box-shadow: var(--shadow-md);
}

.num-btn:active {
  transform: translateY(0);
}

.num-btn.completed {
  opacity: 0.3;
  pointer-events: none;
}

.num-btn.num-btn--active {
  background: var(--color-primary);
  border-color: var(--color-primary);
  color: #fff;
  box-shadow: 0 4px 12px var(--color-primary-glow);
}

/* ===== Game Tip ===== */
.game-tip {
  text-align: center;
  font-size: 0.8rem;
  color: var(--color-text-muted);
  margin-bottom: 14px;
  min-height: 1.2em;
  transition: all var(--transition);
}

.game-tip.highlight {
  color: var(--color-primary);
}

/* ===== Numpad Labels ===== */
.numpad-label {
  text-align: center;
  font-size: 0.75rem;
  font-weight: 500;
  color: var(--color-text-secondary);
  margin-bottom: 6px;
}

.numpad-hint {
  text-align: center;
  font-size: 0.7rem;
  color: var(--color-text-muted);
  margin-top: 6px;
  font-style: italic;
}

/* ===== Tooltips ===== */
[data-tooltip] {
  position: relative;
}

[data-tooltip]::after {
  content: attr(data-tooltip);
  position: absolute;
  bottom: calc(100% + 8px);
  left: 50%;
  transform: translateX(-50%) translateY(4px);
  background: var(--color-text);
  color: var(--color-bg);
  font-size: 0.7rem;
  font-weight: 400;
  font-style: normal;
  line-height: 1.4;
  padding: 6px 10px;
  border-radius: var(--radius-sm);
  white-space: nowrap;
  max-width: 220px;
  white-space: normal;
  text-align: center;
  pointer-events: none;
  opacity: 0;
  transition: opacity 0.15s ease, transform 0.15s ease;
  z-index: 20;
  box-shadow: var(--shadow-md);
}

[data-tooltip]::before {
  content: '';
  position: absolute;
  bottom: calc(100% + 2px);
  left: 50%;
  transform: translateX(-50%);
  border: 5px solid transparent;
  border-top-color: var(--color-text);
  pointer-events: none;
  opacity: 0;
  transition: opacity 0.15s ease;
  z-index: 20;
}

[data-tooltip]:hover::after {
  opacity: 1;
  transform: translateX(-50%) translateY(0);
}

[data-tooltip]:hover::before {
  opacity: 1;
}

@media (max-width: 480px) {
  [data-tooltip]::after,
  [data-tooltip]::before {
    display: none;
  }
}

/* ===== Rules Modal ===== */
.modal-backdrop {
  position: fixed;
  inset: 0;
  background: rgba(0, 0, 0, 0.5);
  backdrop-filter: blur(4px);
  display: flex;
  align-items: center;
  justify-content: center;
  z-index: 100;
  opacity: 0;
  pointer-events: none;
  transition: opacity 0.3s ease;
  padding: 16px;
}

.modal-backdrop.visible {
  opacity: 1;
  pointer-events: all;
}

.modal {
  background: var(--color-surface);
  border-radius: var(--radius-xl);
  max-width: 520px;
  width: 100%;
  max-height: 80vh;
  overflow-y: auto;
  box-shadow: var(--shadow-xl);
  transform: translateY(16px) scale(0.97);
  transition: transform 0.3s cubic-bezier(0.34, 1.56, 0.64, 1);
}

.modal-backdrop.visible .modal {
  transform: translateY(0) scale(1);
}

.modal__header {
  display: flex;
  align-items: center;
  justify-content: space-between;
  padding: 20px 24px 0;
  position: sticky;
  top: 0;
  background: var(--color-surface);
  z-index: 1;
}

.modal__title {
  font-family: var(--font-display);
  font-size: 1.15rem;
  font-weight: 700;
}

.modal__close {
  width: 32px;
  height: 32px;
  display: flex;
  align-items: center;
  justify-content: center;
  border-radius: 50%;
  font-size: 1.4rem;
  color: var(--color-text-muted);
  transition: all var(--transition);
  flex-shrink: 0;
}

.modal__close:hover {
  background: var(--color-surface-alt);
  color: var(--color-text);
}

.modal__body {
  padding: 20px 24px 24px;
}

.rules-section {
  margin-bottom: 20px;
}

.rules-section:last-child {
  margin-bottom: 0;
}

.rules-section h3 {
  font-family: var(--font-display);
  font-size: 0.85rem;
  font-weight: 600;
  color: var(--color-primary);
  margin-bottom: 8px;
  text-transform: uppercase;
  letter-spacing: 0.03em;
}

.rules-section > p {
  font-size: 0.875rem;
  line-height: 1.6;
  color: var(--color-text-secondary);
}

.rules-steps {
  display: flex;
  flex-direction: column;
  gap: 12px;
}

.rules-step {
  display: flex;
  gap: 12px;
  align-items: flex-start;
}

.rules-step__num {
  flex-shrink: 0;
  width: 28px;
  height: 28px;
  display: flex;
  align-items: center;
  justify-content: center;
  background: var(--color-primary);
  color: #fff;
  font-family: var(--font-display);
  font-size: 0.8rem;
  font-weight: 700;
  border-radius: 50%;
}

.rules-step strong {
  display: block;
  font-size: 0.85rem;
  margin-bottom: 2px;
}

.rules-step p {
  font-size: 0.8rem;
  color: var(--color-text-secondary);
  line-height: 1.5;
}

.rules-tools {
  display: flex;
  flex-direction: column;
  gap: 10px;
}

.rules-tool {
  display: flex;
  gap: 12px;
  align-items: flex-start;
}

.rules-tool__icon {
  flex-shrink: 0;
  width: 32px;
  height: 32px;
  display: flex;
  align-items: center;
  justify-content: center;
  background: var(--color-primary-light);
  color: var(--color-primary);
  font-size: 1rem;
  border-radius: var(--radius-sm);
}

.rules-tool strong {
  display: block;
  font-size: 0.85rem;
  margin-bottom: 1px;
}

.rules-tool p {
  font-size: 0.8rem;
  color: var(--color-text-secondary);
  line-height: 1.5;
}

.rules-tool kbd {
  display: inline-block;
  padding: 1px 5px;
  font-family: var(--font-body);
  font-size: 0.7rem;
  background: var(--color-surface-alt);
  border: 1px solid var(--color-border);
  border-radius: 3px;
  color: var(--color-text-secondary);
}

.rules-tips {
  list-style: none;
  display: flex;
  flex-direction: column;
  gap: 8px;
}

.rules-tips li {
  font-size: 0.8rem;
  color: var(--color-text-secondary);
  line-height: 1.5;
  padding-left: 20px;
  position: relative;
}

.rules-tips li::before {
  content: '→';
  position: absolute;
  left: 0;
  color: var(--color-primary);
  font-weight: 600;
}

/* ===== SEO Content ===== */
.seo-content {
  margin-top: 32px;
  padding-top: 24px;
  border-top: 1px solid var(--color-border);
}

.seo-content h2 {
  font-family: var(--font-display);
  font-size: 1.2rem;
  font-weight: 700;
  margin-bottom: 12px;
}

.seo-content h3 {
  font-family: var(--font-display);
  font-size: 0.95rem;
  font-weight: 600;
  margin-top: 20px;
  margin-bottom: 8px;
}

.seo-content p {
  font-size: 0.875rem;
  line-height: 1.7;
  color: var(--color-text-secondary);
  margin-bottom: 8px;
}

.seo-content ul {
  list-style: none;
  padding: 0;
  display: flex;
  flex-direction: column;
  gap: 4px;
  margin-bottom: 8px;
}

.seo-content ul li {
  font-size: 0.85rem;
  color: var(--color-text-secondary);
  padding-left: 18px;
  position: relative;
  line-height: 1.6;
}

.seo-content ul li::before {
  content: '✓';
  position: absolute;
  left: 0;
  color: var(--color-success);
  font-weight: 700;
}

/* FAQ */
.faq {
  margin-top: 20px;
}

.faq summary {
  cursor: pointer;
  list-style: none;
}

.faq summary::-webkit-details-marker {
  display: none;
}

.faq summary h3 {
  display: inline;
  color: var(--color-primary);
}

.faq summary h3::after {
  content: ' ▸';
  font-size: 0.8em;
}

.faq[open] summary h3::after {
  content: ' ▾';
}

.faq__item {
  margin-top: 16px;
}

.faq__item h4 {
  font-size: 0.875rem;
  font-weight: 600;
  margin-bottom: 4px;
}

.faq__item p {
  font-size: 0.825rem;
  color: var(--color-text-secondary);
  line-height: 1.6;
}

/* ===== Footer ===== */
.footer {
  margin-top: 24px;
  padding: 16px 0;
  text-align: center;
  font-size: 0.75rem;
  color: var(--color-text-muted);
  border-top: 1px solid var(--color-border);
}

.footer__links {
  margin-top: 8px;
  display: flex;
  justify-content: center;
  gap: 8px;
  align-items: center;
}

.footer__link {
  font-size: 0.75rem;
  color: var(--color-text-muted);
  text-decoration: none;
  transition: color var(--transition);
  background: none;
  border: none;
  cursor: pointer;
  font-family: inherit;
}

.footer__link:hover {
  color: var(--color-primary);
}

.footer__sep {
  color: var(--color-border);
}

/* ===== Responsive ===== */
@media (max-width: 480px) {
  :root {
    --board-size: calc(100vw - 24px);
  }

  #app {
    padding: 0 12px;
  }

  .header__title {
    font-size: 1.25rem;
  }

  .difficulty-selector {
    gap: 2px;
    padding: 3px;
  }

  .difficulty-btn {
    padding: 5px 10px;
    font-size: 0.75rem;
  }

  .game-stats {
    gap: 24px;
  }

  .tool-btn {
    padding: 8px 12px;
  }

  .num-btn {
    font-size: 1.1rem;
    border-radius: var(--radius-sm);
  }

  .game-bar {
    flex-direction: column;
    align-items: stretch;
  }

  .game-bar .btn--primary {
    align-self: center;
  }
}

@media (max-width: 360px) {
  .difficulty-btn {
    padding: 4px 7px;
    font-size: 0.7rem;
  }

  .controls__tools {
    gap: 4px;
  }

  .tool-btn {
    padding: 6px 8px;
    font-size: 0.65rem;
  }

  .tool-btn span:not(.hint-count) {
    display: none;
  }
}

/* ===== Leaderboard ===== */
.lb-tabs {
  display: flex;
  gap: 4px;
  background: var(--color-surface-alt);
  border-radius: var(--radius-md);
  padding: 4px;
  margin-bottom: 16px;
}

.lb-tab {
  flex: 1;
  padding: 6px 8px;
  border-radius: var(--radius-sm);
  font-size: 0.775rem;
  font-weight: 500;
  color: var(--color-text-secondary);
  transition: all var(--transition);
  text-align: center;
}

.lb-tab:hover {
  color: var(--color-text);
}

.lb-tab.active {
  background: var(--color-primary);
  color: #fff;
  box-shadow: 0 2px 8px var(--color-primary-glow);
}

.lb-list {
  display: flex;
  flex-direction: column;
  gap: 6px;
  min-height: 160px;
}

.lb-empty {
  display: flex;
  align-items: center;
  justify-content: center;
  min-height: 160px;
  font-size: 0.875rem;
  color: var(--color-text-muted);
}

.lb-row {
  display: grid;
  grid-template-columns: 28px 1fr auto auto;
  align-items: center;
  gap: 10px;
  padding: 10px 12px;
  background: var(--color-surface-alt);
  border-radius: var(--radius-md);
  border: 1px solid var(--color-border);
}

.lb-row--gold { border-color: #f59e0b; background: rgba(245, 158, 11, 0.06); }
.lb-row--silver { border-color: #9ca3af; background: rgba(156, 163, 175, 0.06); }
.lb-row--bronze { border-color: #cd7f32; background: rgba(205, 127, 50, 0.06); }

.lb-rank {
  font-family: var(--font-display);
  font-size: 0.85rem;
  font-weight: 700;
  text-align: center;
  color: var(--color-text-muted);
}

.lb-row--gold .lb-rank { color: #f59e0b; }
.lb-row--silver .lb-rank { color: #9ca3af; }
.lb-row--bronze .lb-rank { color: #cd7f32; }

.lb-date {
  font-size: 0.75rem;
  color: var(--color-text-muted);
}

.lb-score {
  font-family: var(--font-display);
  font-size: 0.95rem;
  font-weight: 700;
  color: var(--color-primary);
  text-align: right;
}

.lb-meta {
  display: flex;
  flex-direction: column;
  gap: 1px;
}

.lb-time {
  font-size: 0.8rem;
  font-weight: 600;
  color: var(--color-text);
}

.lb-mistakes {
  font-size: 0.7rem;
  color: var(--color-text-muted);
}

/* ===== Overlay actions ===== */
.overlay-actions {
  display: flex;
  flex-direction: column;
  align-items: center;
  gap: 8px;
}

/* ===== Animations ===== */
@keyframes fadeIn {
  from { opacity: 0; transform: translateY(8px); }
  to { opacity: 1; transform: translateY(0); }
}

.board {
  animation: fadeIn 0.4s ease;
}

/* ===== Accessibility ===== */
@media (prefers-reduced-motion: reduce) {
  *, *::before, *::after {
    animation-duration: 0.01ms !important;
    transition-duration: 0.01ms !important;
  }
}

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