:root {
  --sdk-line: rgba(15, 23, 42, 0.12);
  --sdk-given: rgba(15, 23, 42, 0.92);
  --sdk-user: rgba(37, 99, 235, 0.95);
  --sdk-wrong: rgba(239, 68, 68, 0.98);
  --sdk-sel: rgba(37, 99, 235, 0.12);
  --sdk-peek: rgba(148, 163, 184, 0.18);
}

.sdkHud {
  margin: 10px 0 12px;
  border-radius: 16px;
  padding: 12px 12px;
  border: 1px solid rgba(15, 23, 42, 0.06);
  background: linear-gradient(180deg, rgba(59, 130, 246, 0.08), rgba(34, 197, 94, 0.06));
  box-shadow: 0 10px 24px rgba(2, 6, 23, 0.06);
  display: flex;
  align-items: center;
  justify-content: space-between;
  gap: 12px;
}

.sdkDiffWrap {
  display: grid;
  place-items: center start;
  gap: 4px;
}
.sdkDiffLabel {
  font-size: 12px;
  font-weight: 900;
  color: rgba(15, 23, 42, 0.7);
  letter-spacing: 0.2px;
}
.sdkDiffGrid {
  display: grid;
  grid-auto-flow: column;
  grid-auto-columns: 10px;
  gap: 4px;
  padding: 4px 6px;
  border-radius: 999px;
  background: rgba(255, 255, 255, 0.55);
  border: 1px solid rgba(15, 23, 42, 0.1);
  cursor: pointer;
  user-select: none;
  touch-action: manipulation;
}
.sdkDiffDot {
  width: 10px;
  height: 10px;
  border-radius: 3px;
  border: 1px solid rgba(15, 23, 42, 0.22);
  background: rgba(255, 255, 255, 0.55);
}
.sdkDiffDot.isDone {
  background: rgba(15, 23, 42, 0.92);
  border-color: rgba(15, 23, 42, 0.92);
}
.sdkDiffDot.isCurrent {
  background: rgba(148, 163, 184, 0.92);
  border-color: rgba(148, 163, 184, 0.92);
}

.sdkRight {
  text-align: right;
  display: grid;
  gap: 4px;
  min-width: 120px;
}
.sdkLvText {
  font-weight: 1000;
  font-size: 13px;
  color: rgba(15, 23, 42, 0.82);
}
.sdkHint {
  font-size: 12px;
  color: rgba(100, 116, 139, 0.95);
}

.sdkBoard {
  width: min(460px, 100%);
  aspect-ratio: 1 / 1;
  margin: 0 auto;
  display: grid;
  grid-template-columns: repeat(9, 1fr);
  grid-template-rows: repeat(9, 1fr);
  border: 3px solid var(--sdk-line);
  border-radius: 18px;
  overflow: hidden;
  background: #fff;
  box-shadow: var(--shadow-soft);
}

.sdkCell {
  appearance: none;
  border: 0;
  padding: 0;
  width: 100%;
  height: 100%;
  background: linear-gradient(180deg, #ffffff, #f8fafc);
  border-right: 1px solid rgba(15, 23, 42, 0.14);
  border-bottom: 1px solid rgba(15, 23, 42, 0.14);
  cursor: pointer;
  touch-action: manipulation;
  user-select: none;
  display: grid;
  place-items: center;
  font-weight: 1000;
  font-size: clamp(14px, 3.8vw, 22px);
  transition: background 120ms ease, transform 90ms ease;
  position: relative;
}

.sdkCell:nth-child(9n) {
  border-right: 0;
}
.sdkCell:nth-last-child(-n + 9) {
  border-bottom: 0;
}

/* 粗线：每 3 宫 */
.sdkCell.v3 {
  border-right: 3px solid var(--sdk-line);
}
.sdkCell.h3 {
  border-bottom: 3px solid var(--sdk-line);
}

.sdkCell:active {
  transform: scale(0.985);
}

.sdkCell.given {
  color: var(--sdk-given);
}
.sdkCell.user {
  color: var(--sdk-user);
}
.sdkCell.wrong {
  color: var(--sdk-wrong);
}

.sdkCell.selected {
  background: var(--sdk-sel);
}
.sdkCell.peek {
  background: var(--sdk-peek);
}

.sdkPad {
  margin: 14px 0 10px;
  display: grid;
  gap: 10px;
}

.sdkNums {
  display: grid;
  grid-template-columns: repeat(9, 1fr);
  gap: 8px;
}

.sdkNumBtn {
  border: 1px solid rgba(15, 23, 42, 0.12);
  border-radius: 12px;
  background: rgba(255, 255, 255, 0.75);
  box-shadow: 0 10px 22px rgba(2, 6, 23, 0.06);
  padding: 10px 0;
  font-size: 16px;
  font-weight: 1000;
  cursor: pointer;
  touch-action: manipulation;
}
.sdkNumBtn:active {
  transform: scale(0.99);
}

.sdkBtnSecondary {
  background: linear-gradient(180deg, rgba(37, 99, 235, 0.92), rgba(29, 78, 216, 0.92));
  box-shadow: 0 10px 24px rgba(37, 99, 235, 0.2);
}

.sdkEraseBtn {
  width: 100%;
  border: 1px solid rgba(15, 23, 42, 0.12);
  border-radius: 999px;
  background: rgba(255, 255, 255, 0.75);
  box-shadow: 0 10px 22px rgba(2, 6, 23, 0.06);
  padding: 11px 14px;
  font-size: 15px;
  font-weight: 900;
  cursor: pointer;
  touch-action: manipulation;
}
.sdkEraseBtn:active {
  transform: scale(0.99);
}

.sdkActions {
  display: grid;
  grid-template-columns: 1fr 1fr;
  gap: 10px;
}
.sdkActions a.btn {
  grid-column: 1 / -1;
}
.sdkActions .btn {
  width: 100%;
}

@media (max-width: 420px) {
  .sdkHud {
    padding: 8px 10px;
    border-radius: 14px;
  }
  .sdkDiffGrid {
    grid-auto-columns: 9px;
    gap: 3px;
    padding: 3px 5px;
  }
  .sdkDiffDot {
    width: 9px;
    height: 9px;
  }
  .sdkBoard {
    border-radius: 16px;
    height: min(380px, 86vw);
  }
  .sdkNums {
    gap: 6px;
  }
  .sdkNumBtn {
    padding: 9px 0;
    border-radius: 12px;
  }
  .sdkEraseBtn {
    padding: 10px 14px;
  }
}