:root {
  --bg-top: #f1ead9;
  --bg-bottom: #d6c9b2;
  --ink: #312f27;
  --ink-soft: #6a6458;
  --panel: rgba(255, 251, 241, 0.86);
  --line-soft: #8c8474;
  --line-strong: #2a2821;
  --cage-line: #3e3b32;
  --ok: #1f8052;
  --warn: #b0312c;
  --selected: #91acc8;
}

* {
  box-sizing: border-box;
}

html,
body {
  height: 100%;
}

body {
  margin: 0;
  overflow: hidden;
  color: var(--ink);
  font-family: "Trebuchet MS", "Segoe UI Variable Text", "Microsoft YaHei", sans-serif;
  background:
    radial-gradient(circle at 10% 20%, rgba(255, 255, 255, 0.65) 0 18%, transparent 30%),
    radial-gradient(circle at 90% 10%, rgba(255, 255, 255, 0.4) 0 22%, transparent 32%),
    linear-gradient(165deg, var(--bg-top), var(--bg-bottom));
}

.page {
  width: min(920px, 100vw);
  height: 100dvh;
  margin: 0 auto;
  padding: 8px;
  display: grid;
  grid-template-rows: auto auto minmax(0, 1fr) auto;
  gap: 8px;
  overflow: hidden;
}

.hero {
  padding: 8px 10px;
  border-radius: 10px;
  background: linear-gradient(130deg, rgba(255, 255, 255, 0.8), rgba(243, 235, 220, 0.82));
  border: 1px solid rgba(71, 63, 49, 0.2);
  box-shadow: 0 8px 14px rgba(45, 36, 20, 0.08);
}

.eyebrow {
  margin: 0;
  color: var(--ink-soft);
  letter-spacing: 0.15em;
  text-transform: uppercase;
  font-size: 12px;
}

h1 {
  margin: 2px 0 0;
  font-size: clamp(20px, 3.8vw, 30px);
  line-height: 1.1;
}

.subtitle {
  margin: 4px 0 0;
  font-size: 13px;
  color: var(--ink-soft);
}

.panel,
.board-wrap,
.pad-wrap {
  padding: 8px;
  border-radius: 10px;
  background: var(--panel);
  border: 1px solid rgba(63, 56, 42, 0.2);
}

.controls {
  display: flex;
  flex-wrap: wrap;
  gap: 8px;
  align-items: center;
}

.difficulty-wrap {
  display: inline-flex;
  align-items: center;
  gap: 8px;
  height: 34px;
  padding: 0 10px;
  border-radius: 10px;
  background: rgba(83, 76, 62, 0.12);
  color: #3c372d;
  font-weight: 700;
}

.difficulty-wrap select {
  border: 1px solid rgba(69, 62, 49, 0.35);
  border-radius: 8px;
  padding: 4px 8px;
  background: #fffdf7;
  color: #332f25;
  font: inherit;
}

button {
  border: 0;
  padding: 8px 12px;
  border-radius: 8px;
  cursor: pointer;
  font-weight: 700;
  color: #fdf9ef;
  background: linear-gradient(180deg, #5f5a4b, #3e3a2e);
  transition: transform 120ms ease, box-shadow 120ms ease;
}

button:hover {
  transform: translateY(-1px);
  box-shadow: 0 8px 14px rgba(44, 38, 26, 0.18);
}

button:active {
  transform: translateY(0);
}

.status {
  margin: 6px 2px 0;
  min-height: 20px;
  font-size: 14px;
  color: var(--ink-soft);
}

.status.ok {
  color: var(--ok);
  font-weight: 700;
}

.status.warn {
  color: var(--warn);
  font-weight: 700;
}

.board-wrap {
  min-height: 0;
  display: grid;
  place-items: center;
}

.board {
  width: min(88vw, 640px);
  height: min(88vw, 640px);
  aspect-ratio: 1 / 1;
  position: relative;
  display: grid;
  grid-template-columns: repeat(9, 1fr);
  grid-template-rows: repeat(9, 1fr);
  box-shadow: 0 10px 16px rgba(40, 34, 24, 0.18);
  animation: boardIn 360ms ease both;
}

@keyframes boardIn {
  from {
    opacity: 0;
    transform: translateY(8px) scale(0.98);
  }
  to {
    opacity: 1;
    transform: translateY(0) scale(1);
  }
}

.cell {
  position: relative;
  z-index: 1;
  background: #fffdf8;
  overflow: hidden;
  cursor: pointer;
}

.cell.selected {
  background: rgba(145, 172, 200, 0.23);
}

.cage-layer {
  position: absolute;
  inset: 0;
  z-index: 4;
  pointer-events: none;
}

.cage-edge {
  position: absolute;
}

.cage-edge.top,
.cage-edge.bottom {
  border-top: 2px dashed var(--cage-line);
}

.cage-edge.left,
.cage-edge.right {
  border-left: 2px dashed var(--cage-line);
}

.cell-value {
  position: absolute;
  inset: 0;
  z-index: 5;
  display: flex;
  align-items: center;
  justify-content: center;
  color: #1f4675;
  font-size: clamp(20px, 3.8vw, 34px);
  font-weight: 600;
  pointer-events: none;
}

.notes-grid {
  position: absolute;
  left: 2px;
  right: 2px;
  top: 12px;
  bottom: 2px;
  z-index: 3;
  display: grid;
  grid-template-columns: repeat(3, 1fr);
  grid-template-rows: repeat(3, 1fr);
  pointer-events: none;
}

.notes-grid .note {
  display: flex;
  align-items: center;
  justify-content: center;
  font-size: clamp(10px, 1.3vw, 14px);
  color: #5f5b4f;
  opacity: 0;
}

.notes-grid .note.visible {
  opacity: 1;
}

.cell.has-value .notes-grid {
  opacity: 0;
}

.cell .clue {
  position: absolute;
  top: 2px;
  left: 4px;
  z-index: 6;
  font-size: clamp(9px, 1.3vw, 12px);
  line-height: 1;
  color: #454031;
  pointer-events: none;
}

.cell.given .cell-value {
  color: #18150f;
  font-weight: 700;
}

.cell.value-error .cell-value {
  color: #c8392f;
  font-weight: 700;
}

.cell.hint {
  background: #ebf8e9;
}

.pad-wrap {
  display: grid;
  gap: 8px;
}

.pad-top {
  display: flex;
  align-items: center;
  justify-content: space-between;
  gap: 10px;
}

.note-toggle {
  min-width: 96px;
  background: linear-gradient(180deg, #6c8aa4, #4a6680);
}

.note-toggle.active {
  background: linear-gradient(180deg, #2f8f67, #206247);
}

.pad-tip {
  color: var(--ink-soft);
  font-size: 14px;
}

.number-pad {
  display: grid;
  grid-template-columns: repeat(10, minmax(0, 1fr));
  gap: 6px;
}

.num-btn {
  padding: 8px 0;
  font-size: clamp(16px, 2vw, 24px);
  line-height: 1;
  background: linear-gradient(180deg, #4f6b87, #34495f);
}

.num-btn.erase {
  font-size: 16px;
  background: linear-gradient(180deg, #8b514c, #663833);
}

@media (max-width: 720px) {
  .page {
    width: 100vw;
    padding: 6px;
  }

  .eyebrow {
    font-size: 10px;
  }

  .subtitle {
    display: none;
  }

  .difficulty-wrap {
    flex: 1 1 100%;
    justify-content: center;
    height: 32px;
  }

  .controls button {
    flex: 1 1 32%;
    padding: 7px 8px;
  }

  .pad-top {
    align-items: center;
  }

  .pad-tip {
    font-size: 12px;
  }

  .number-pad {
    grid-template-columns: repeat(5, minmax(0, 1fr));
    gap: 5px;
  }
}

@media (max-height: 760px) {
  .eyebrow,
  .subtitle {
    display: none;
  }

  .hero {
    padding: 6px 10px;
  }

  .panel,
  .board-wrap,
  .pad-wrap {
    padding: 6px;
  }

  .status {
    min-height: 16px;
    font-size: 12px;
    margin-top: 4px;
  }
}