:root {
  --bg: #080b14;
  --bg-soft: #11182b;
  --text: #f5f7ff;
  --muted: rgba(245, 247, 255, 0.66);
  --accent: #2dd4bf;
  --accent-2: #38bdf8;
  --danger: #fb7185;
  --ok: #22c55e;
  --board-edge: rgba(255, 255, 255, 0.1);
  --cell-bg: rgba(255, 255, 255, 0.04);
  --cell-selected: rgba(45, 212, 191, 0.2);
  --cell-related: rgba(56, 189, 248, 0.12);
  --cell-given: rgba(255, 255, 255, 0.08);
  --cell-conflict: rgba(251, 113, 133, 0.35);
  --safe-left: env(safe-area-inset-left, 0px);
  --safe-right: env(safe-area-inset-right, 0px);
  --safe-top: max(env(safe-area-inset-top, 0px), 56px);
  --safe-bottom: max(env(safe-area-inset-bottom, 0px), 20px);
  --host-back-gutter: 56px;
}

* {
  box-sizing: border-box;
  -webkit-tap-highlight-color: transparent;
}

html,
body {
  margin: 0;
  padding: 0;
  width: 100%;
  min-height: 100%;
  background: var(--bg);
  color: var(--text);
  font-family: 'DM Sans', ui-sans-serif, system-ui, -apple-system, sans-serif;
  touch-action: manipulation;
}

body {
  position: relative;
  overflow: hidden;
}

.bg-orb {
  position: fixed;
  border-radius: 999px;
  filter: blur(70px);
  opacity: 0.45;
  pointer-events: none;
}

.bg-orb-a {
  width: 42vmax;
  height: 42vmax;
  left: -14vmax;
  top: -10vmax;
  background: radial-gradient(circle at center, rgba(45, 212, 191, 0.8), rgba(45, 212, 191, 0));
}

.bg-orb-b {
  width: 46vmax;
  height: 46vmax;
  right: -18vmax;
  bottom: -16vmax;
  background: radial-gradient(circle at center, rgba(56, 189, 248, 0.75), rgba(56, 189, 248, 0));
}

.app {
  position: relative;
  z-index: 1;
  width: 100%;
  max-width: 660px;
  min-height: min(100vh, 100dvh);
  margin: 0 auto;
  padding-top: max(10px, calc(var(--safe-top) + 4px));
  padding-bottom: max(10px, calc(var(--safe-bottom) + 8px));
  padding-left: max(10px, calc(var(--safe-left) + 10px));
  padding-right: max(10px, calc(var(--safe-right) + 10px));
  display: grid;
  grid-template-rows: auto auto auto auto;
  gap: 20px;
  justify-items: center;
  align-content: center;
}

.hud {
  display: grid;
  grid-template-columns: repeat(3, minmax(0, 1fr));
  gap: 8px;
  width: min(76vw, 360px);
}

.chip {
  background: linear-gradient(160deg, rgba(255, 255, 255, 0.1), rgba(255, 255, 255, 0.04));
  border: 1px solid rgba(255, 255, 255, 0.14);
  border-radius: 12px;
  padding: 8px 10px;
  display: grid;
  gap: 3px;
}

.chip-alert {
  border-color: rgba(251, 113, 133, 0.5);
}

.chip-label {
  font-size: 0.7rem;
  color: var(--muted);
  text-transform: uppercase;
  letter-spacing: 0.1em;
  font-weight: 700;
}

.chip-value {
  font-size: 1.05rem;
  font-weight: 800;
  font-family: 'Space Grotesk', 'DM Sans', sans-serif;
}

.chip-difficulty {
  align-content: start;
}

.chip-row {
  display: flex;
  align-items: center;
  justify-content: space-between;
  gap: 8px;
}

.chip-refresh-btn {
  width: 24px;
  height: 24px;
  border: 0;
  border-radius: 999px;
  display: grid;
  place-items: center;
  padding: 0;
  background: rgba(255, 255, 255, 0.12);
  color: rgba(245, 247, 255, 0.9);
  font-size: 14px;
  font-weight: 800;
  line-height: 1;
}

.chip-refresh-btn:active {
  transform: scale(0.94);
  background: rgba(45, 212, 191, 0.28);
}

.chip-refresh-btn:disabled {
  opacity: 0.55;
}

.board-wrap {
  display: grid;
  place-items: center;
  margin-top: 14px;
  margin-bottom: 14px;
}

.board {
  width: min(76vw, 360px);
  aspect-ratio: 1;
  background: var(--bg-soft);
  border-radius: 14px;
  border: 2px solid var(--board-edge);
  box-shadow: 0 16px 48px rgba(0, 0, 0, 0.38), inset 0 0 0 1px rgba(255, 255, 255, 0.03);
  display: grid;
  grid-template-columns: repeat(4, 1fr);
  grid-template-rows: repeat(4, 1fr);
  overflow: hidden;
}

.cell {
  position: relative;
  border: 1px solid rgba(255, 255, 255, 0.06);
  background: var(--cell-bg);
  color: var(--text);
  font-size: clamp(1.25rem, 4.2vw, 2rem);
  font-weight: 700;
  font-family: 'Space Grotesk', 'DM Sans', sans-serif;
  display: grid;
  place-items: center;
  padding: 0;
  outline: none;
}

.cell.corner-tl {
  border-top-left-radius: 12px;
}

.cell.corner-tr {
  border-top-right-radius: 12px;
}

.cell.corner-bl {
  border-bottom-left-radius: 12px;
}

.cell.corner-br {
  border-bottom-right-radius: 12px;
}

.cell.box-right {
  border-right-color: rgba(255, 255, 255, 0.3);
}

.cell.box-end {
  border-bottom-color: rgba(255, 255, 255, 0.3);
}

.cell.given {
  background: var(--cell-given);
  color: #ffffff;
}

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

.cell.selected::after {
  content: "";
  position: absolute;
  inset: 0;
  border: 2px solid rgba(45, 212, 191, 0.8);
  border-radius: inherit;
  pointer-events: none;
}

.cell.related {
  background: var(--cell-related);
}

.cell.conflict {
  background: var(--cell-conflict);
}

.cell .value {
  pointer-events: none;
}

.notes-grid {
  position: absolute;
  inset: 3px;
  display: grid;
  grid-template-columns: repeat(2, 1fr);
  grid-template-rows: repeat(2, 1fr);
  gap: 0;
  pointer-events: none;
}

.note {
  font-size: clamp(0.58rem, 2.2vw, 0.9rem);
  font-weight: 700;
  color: rgba(245, 247, 255, 0.8);
  display: grid;
  place-items: center;
}

.controls {
  display: grid;
  gap: 8px;
  width: min(76vw, 360px);
}

.controls-row {
  display: grid;
  gap: 8px;
}

.controls-row-numpad {
  grid-template-columns: repeat(4, minmax(0, 1fr));
}

.controls-row-actions {
  grid-template-columns: repeat(2, minmax(0, 1fr));
}

.num-btn,
.action-btn {
  height: 46px;
  border: 0;
  border-radius: 11px;
  color: var(--text);
  background: linear-gradient(180deg, rgba(255, 255, 255, 0.12), rgba(255, 255, 255, 0.06));
  font-weight: 800;
  font-size: 1rem;
  font-family: 'Space Grotesk', 'DM Sans', sans-serif;
}

.num-btn:active,
.action-btn:active {
  transform: scale(0.97);
}

.action-btn.active {
  background: linear-gradient(180deg, rgba(45, 212, 191, 0.42), rgba(45, 212, 191, 0.25));
  box-shadow: inset 0 0 0 1px rgba(45, 212, 191, 0.75);
}

.status-banner {
  min-height: 22px;
  text-align: center;
  font-size: 0.92rem;
  color: var(--muted);
  font-weight: 700;
}

.status-banner.success {
  color: var(--ok);
}

.status-banner.danger {
  color: var(--danger);
}

@media (max-width: 560px) {
  .app {
    gap: 8px;
  }

  .chip {
    padding: 7px 8px;
  }

  .chip-value {
    font-size: 0.96rem;
  }

  .num-btn,
  .action-btn {
    height: 42px;
    font-size: 0.92rem;
  }
}

@media (min-width: 700px) {
  .app {
    max-width: 760px;
    gap: 24px;
    padding-top: max(14px, calc(var(--safe-top) + 8px));
    padding-bottom: max(14px, calc(var(--safe-bottom) + 12px));
    padding-left: max(16px, calc(var(--safe-left) + 16px));
    padding-right: max(16px, calc(var(--safe-right) + 16px));
  }

  .hud,
  .controls {
    width: min(70vw, 500px);
    gap: 10px;
  }

  .chip {
    border-radius: 14px;
    padding: 10px 12px;
  }

  .chip-label {
    font-size: 0.78rem;
  }

  .chip-value {
    font-size: 1.2rem;
  }

  .chip-refresh-btn {
    width: 28px;
    height: 28px;
    font-size: 16px;
  }

  .board-wrap {
    margin-top: 18px;
    margin-bottom: 18px;
  }

  .board {
    width: min(70vw, 500px);
    border-radius: 18px;
  }

  .cell {
    font-size: clamp(1.6rem, 3.6vw, 2.5rem);
  }

  .note {
    font-size: clamp(0.72rem, 1.8vw, 1.05rem);
  }

  .controls {
    gap: 10px;
  }

  .controls-row {
    gap: 10px;
  }

  .num-btn,
  .action-btn {
    height: 56px;
    border-radius: 14px;
    font-size: 1.15rem;
  }

  .status-banner {
    min-height: 26px;
    font-size: 1.05rem;
  }
}

@media (min-width: 900px) {
  .app {
    max-width: 880px;
    gap: 28px;
  }

  .hud,
  .controls,
  .board {
    width: min(58vw, 600px);
  }

  .cell {
    font-size: clamp(1.9rem, 3.2vw, 2.9rem);
  }

  .num-btn,
  .action-btn {
    height: 62px;
    font-size: 1.25rem;
  }
}