:root {
  --s-card-bg: rgba(255,255,255,0.65);
  --s-card-border: rgba(127,127,127,0.35);
  --s-muted: rgba(0,0,0,0.65);
  --s-strong: rgba(0,0,0,0.9);
  --s-accent: var(--accent-color, #007acc);
  --s-block-a: rgba(0, 122, 204, 0.06);
  --s-block-b: rgba(181, 232, 83, 0.06);
  --s-highlight: rgba(255, 204, 0, 0.20);

  /* Board grid lines */
  --s-grid-line: rgba(127, 127, 127, 0.22);
  --s-box-line: rgba(127, 127, 127, 0.55);
}

html.dark-mode {
  --s-card-bg: rgba(0,0,0,0.18);
  --s-card-border: rgba(200,200,200,0.18);
  --s-muted: rgba(255,255,255,0.72);
  --s-strong: rgba(255,255,255,0.9);
  --s-block-a: rgba(0, 122, 204, 0.14);
  --s-block-b: rgba(181, 232, 83, 0.12);
  --s-highlight: rgba(255, 204, 0, 0.22);

  /* Board grid lines (stronger contrast in dark mode) */
  --s-grid-line: rgba(255, 255, 255, 0.12);
  --s-box-line: rgba(255, 255, 255, 0.38);
}

.sudoku-app {
  max-width: 1040px;
  margin: 0 auto;
}

.sudoku-header {
  display: flex;
  justify-content: space-between;
  align-items: flex-start;
  gap: 1rem;
}

.sudoku-title {
  margin-bottom: 0.2rem;
}

.sudoku-subtitle {
  margin-top: 0;
  opacity: 0.9;
}

.sudoku-header__right {
  display: flex;
  gap: 0.5rem;
  align-items: center;
  flex-wrap: wrap;
  justify-content: flex-end;
}

.pill {
  border: 1px solid var(--s-card-border);
  border-radius: 999px;
  padding: 0.18rem 0.6rem;
  font-size: 0.78rem;
  opacity: 0.9;
  background: var(--s-card-bg);
}

.pill--link {
  text-decoration: none;
}

.card {
  margin-top: 1rem;
  border: 1px solid var(--s-card-border);
  background: var(--s-card-bg);
  border-radius: 14px;
  padding: 1rem;
  backdrop-filter: blur(10px);
}

.mode {
  display: flex;
  align-items: center;
  justify-content: space-between;
  gap: 0.8rem;
  margin-bottom: 0.9rem;
}

.mode__label {
  font-weight: 800;
  opacity: 0.85;
}

.mode__buttons {
  display: flex;
  gap: 0.5rem;
  flex-wrap: wrap;
  justify-content: flex-end;
}

.hidden { display: none !important; }

.tabs {
  display: flex;
  gap: 0.4rem;
  margin-bottom: 0.8rem;
}

.tab {
  appearance: none;
  border: 1px solid var(--s-card-border);
  background: transparent;
  color: inherit;
  padding: 0.45rem 0.7rem;
  border-radius: 10px;
  cursor: pointer;
  opacity: 0.9;
}

.tab--active {
  border-color: rgba(127,127,127,0.6);
  box-shadow: 0 10px 30px rgba(0,0,0,0.08);
}

.panel { display: none; }
.panel--active { display: block; }

.form-grid {
  display: grid;
  grid-template-columns: repeat(auto-fit, minmax(220px, 1fr));
  gap: 0.85rem;
}

.field__label {
  display: block;
  font-size: 0.85rem;
  opacity: 0.85;
  margin-bottom: 0.3rem;
}

.field__input {
  width: 100%;
  padding: 0.55rem 0.6rem;
  border-radius: 10px;
  border: 1px solid var(--s-card-border);
  background: rgba(255,255,255,0.75);
  color: #111;
}

html.dark-mode .field__input {
  background: rgba(0,0,0,0.25);
  color: rgba(255,255,255,0.92);
}

.actions {
  display: flex;
  gap: 0.8rem;
  align-items: center;
  margin-top: 0.85rem;
}

.hint {
  font-size: 0.85rem;
  opacity: 0.85;
}

.btn {
  border: 1px solid var(--s-card-border);
  background: transparent;
  color: inherit;
  padding: 0.5rem 0.75rem;
  border-radius: 10px;
  cursor: pointer;
  transition: none;
}

.btn:hover {
  /* Override global theme (.btn:hover) gradient/shading; keep hover minimal */
  transform: none;
  background: transparent;
  box-shadow: none;
  text-shadow: none;
  filter: none;
}

.btn:active,
.btn:focus {
  background: transparent;
  box-shadow: none;
  text-shadow: none;
}

.tab:hover,
.tab:active,
.tab:focus {
  background: transparent;
  box-shadow: none;
  text-shadow: none;
  filter: none;
}

.key:hover,
.key:active,
.key:focus {
  background: rgba(255,255,255,0.5);
  box-shadow: none;
  text-shadow: none;
  filter: none;
}

html.dark-mode .key:hover,
html.dark-mode .key:active,
html.dark-mode .key:focus {
  background: rgba(0,0,0,0.14);
}

.btn--primary {
  border-color: rgba(0,122,204,0.55);
  background: rgba(0,122,204,0.12);
}

.btn--danger {
  border-color: rgba(255, 59, 48, 0.5);
  background: rgba(255, 59, 48, 0.10);
}

.room-top {
  display: flex;
  justify-content: space-between;
  gap: 1rem;
  align-items: flex-start;
}

.room-title {
  opacity: 0.75;
  font-size: 0.85rem;
}

.room-id {
  font-size: 1.25rem;
  font-weight: 800;
  letter-spacing: 0.08em;
}

.room-sub {
  margin-top: 0.25rem;
  opacity: 0.85;
}

.room-actions {
  display: flex;
  gap: 0.5rem;
  align-items: center;
  flex-wrap: wrap;
}

.players {
  margin-top: 0.9rem;
  display: grid;
  grid-template-columns: repeat(auto-fit, minmax(220px, 1fr));
  gap: 0.8rem;
}

.player {
  border: 1px solid var(--s-card-border);
  border-radius: 12px;
  padding: 0.8rem;
}

.player-name {
  font-weight: 700;
}

.player-meta {
  margin-top: 0.2rem;
  opacity: 0.8;
  font-size: 0.85rem;
}

.game-top {
  display: flex;
  justify-content: space-between;
  gap: 1rem;
  align-items: flex-start;
  flex-wrap: wrap;
}

.game-meta {
  display: flex;
  gap: 1rem;
  flex-wrap: wrap;
}

.meta-label {
  font-size: 0.78rem;
  opacity: 0.75;
}

.meta-value {
  font-weight: 800;
}

.board-wrap {
  margin-top: 1rem;
  display: grid;
  width: 100%;
  max-width: calc(600px + 180px + 1rem);
  margin-inline: auto;
  grid-template-columns: minmax(0, 1fr) minmax(160px, 180px);
  gap: 1rem;
  align-items: start;
}

@media (max-width: 860px) {
  .board-wrap {
    grid-template-columns: minmax(0, 1fr);
    max-width: 600px;
  }
}

.board {
  display: grid;
  grid-template-columns: repeat(9, 1fr);
  width: 100%;
  max-width: 600px;
  box-sizing: border-box;
  border: 2px solid var(--s-box-line);
  border-radius: 12px;
  overflow: hidden;
}

/* Solved board: subtle glow + lock cursor */
.board--solved {
  box-shadow:
    0 16px 46px rgba(0,0,0,0.10),
    0 0 0 2px rgba(181, 232, 83, 0.25);
}

.board--solved .cell {
  cursor: default;
}

/* Celebration overlay (confetti/sprinkles) */
.board-wrap {
  position: relative;
}

.sudoku-celebrate-layer {
  position: absolute;
  left: 0;
  top: 0;
  right: 0;
  bottom: 0;
  pointer-events: none;
  overflow: hidden;
  z-index: 5;
}

.sudoku-confetti {
  display: block;
  position: absolute;
  top: -12px;
  transform: translate3d(0, 0, 0);
  will-change: transform, opacity;
  animation: sudoku-confetti-fall var(--confetti-dur, 2.6s) ease-in forwards;
  animation-delay: var(--confetti-delay, 0s);
}

@keyframes sudoku-confetti-fall {
  0% {
    transform: translate3d(0, -10px, 0) rotate(0deg);
    opacity: 0;
  }
  5% {
    opacity: 0.95;
  }
  100% {
    transform:
      translate3d(var(--confetti-drift, 0px), 520px, 0)
      rotate(var(--confetti-rot, 360deg));
    opacity: 0;
  }
}

@media (prefers-reduced-motion: reduce) {
  .sudoku-celebrate-layer { display: none; }
}

.cell {
  position: relative;
  aspect-ratio: 1;
  display: flex;
  align-items: center;
  justify-content: center;
  border: 1px solid var(--s-grid-line);
  background: rgba(255,255,255,0.5);
  user-select: none;
  cursor: pointer;
  font-weight: 800;
  font-size: 1.05rem;
}

/* Subgrid styling (alternating 3x3 blocks) */
.cell--block-a {
  /* keep subtle; block separation is primarily via box lines */
  background: inherit;
}

.cell--block-b {
  background: inherit;
}

html.dark-mode .cell--block-a {
  background: inherit;
}

html.dark-mode .cell--block-b {
  background: inherit;
}

/* Highlight all identical numbers to selected cell */
.cell--same {
  background: var(--s-highlight) !important;
}

html.dark-mode .cell {
  background: rgba(0,0,0,0.14);
}

.cell--given {
  opacity: 0.95;
}

.cell--selected {
  outline: 2px solid rgba(0,122,204,0.7);
  z-index: 2;
}

.cell--peer {
  outline: 2px solid rgba(181,232,83,0.55);
}

.cell--conflict {
  background: rgba(255, 59, 48, 0.12);
}

/* Conflict state needs extra contrast in dark mode */
html.dark-mode .cell--conflict {
  background: rgba(255, 59, 48, 0.24);
  outline: 2px solid rgba(255, 59, 48, 0.50);
  outline-offset: -2px;
}

/* thicker borders for 3x3 boxes */
.cell[data-c="2"], .cell[data-c="5"] {
  border-right-width: 2px;
  border-right-color: var(--s-box-line);
}

.cell[data-r="2"], .cell[data-r="5"] {
  border-bottom-width: 2px;
  border-bottom-color: var(--s-box-line);
}

.keypad {
  border: 1px solid var(--s-card-border);
  border-radius: 12px;
  padding: 0.8rem;
  width: 100%;
  max-width: 180px;
  box-sizing: border-box;
  display: grid;
  grid-template-columns: repeat(3, 1fr);
  gap: 0.55rem;
  background: rgba(255,255,255,0.35);
}

@media (max-width: 860px) {
  .keypad {
    max-width: 360px;
    justify-self: center;
  }
}

html.dark-mode .keypad {
  background: rgba(0,0,0,0.1);
}

.key {
  border: 1px solid rgba(127,127,127,0.35);
  border-radius: 10px;
  padding: 0.6rem 0;
  font-weight: 800;
  cursor: pointer;
  background: rgba(255,255,255,0.5);
  /* Ensure keypad digits are readable in both themes.
     (In dark mode, global button styles can make text too dark.) */
  color: var(--s-strong);
}

html.dark-mode .key {
  background: rgba(0,0,0,0.14);
}

.toast {
  position: fixed;
  left: 50%;
  bottom: 26px;
  transform: translateX(-50%);
  padding: 0.6rem 0.8rem;
  border-radius: 999px;
  border: 1px solid rgba(127,127,127,0.35);
  background: rgba(0,0,0,0.82);
  color: rgba(255,255,255,0.92);
  opacity: 0;
  pointer-events: none;
  transition: opacity 150ms ease, transform 150ms ease;
}

.toast--show {
  opacity: 1;
  transform: translateX(-50%) translateY(-3px);
}