.su-board {
  display: grid;
  grid-template-columns: repeat(9, 1fr);
  width: 100%;
  max-width: 480px;
  margin: 0 auto;
  aspect-ratio: 1 / 1;
  background: rgba(0, 0, 0, 0.3);
  border: 2px solid rgba(255, 255, 255, 0.3);
  border-radius: 8px;
}
.su-cell {
  border: 1px solid rgba(255, 255, 255, 0.08);
  background: rgba(255, 255, 255, 0.02);
  color: #eaf6ff;
  font-weight: 700;
  font-size: clamp(0.7rem, 2.4vw, 1.1rem);
  cursor: pointer;
  aspect-ratio: 1 / 1;
}
.su-cell--bl { border-left: 2px solid rgba(255, 255, 255, 0.3); }
.su-cell--bt { border-top: 2px solid rgba(255, 255, 255, 0.3); }
.su-cell--br { border-right: 2px solid rgba(255, 255, 255, 0.3); }
.su-cell--bb { border-bottom: 2px solid rgba(255, 255, 255, 0.3); }
.su-cell--given { color: #9fd0ff; background: rgba(79, 223, 255, 0.06); cursor: default; }
.su-cell--sel { background: rgba(255, 179, 71, 0.22); }
.su-cell--bad { color: #fb7185; background: rgba(251, 113, 133, 0.12); }

.su-pad {
  display: grid;
  grid-template-columns: repeat(5, 1fr);
  gap: 0.4rem;
  max-width: 480px;
  margin: 0.8rem auto 0;
}
.su-key {
  padding: 0.6rem 0;
  border-radius: 10px;
  border: 1px solid rgba(255, 255, 255, 0.16);
  background: rgba(255, 255, 255, 0.06);
  color: #eaf6ff;
  font-weight: 800;
  cursor: pointer;
}
.su-key:hover { background: rgba(79, 223, 255, 0.16); }
.su-key--erase { grid-column: span 5; color: #ffb0b0; }