.reference-cell,#reference-preview{position:absolute;box-sizing:border-box;border:1.5px solid #83e5fa;background:#70d6ed20;box-shadow:inset 0 0 10px #70d6ed33,0 0 5px #70d6ed33;border-radius:3px;pointer-events:none}
.reference-cell span{position:absolute;right:2px;top:1px;color:#b8f1ff;font-size:clamp(7px,2cqw,10px);font-weight:600;line-height:1;opacity:.7}
#reference-preview{z-index:2;background:#70d6ed0e;box-shadow:none;border-style:dashed;opacity:.7}
.reference-cell.just-marked{animation:cell-mark-pulse .55s ease-out}
.board.reference-placing{outline:1px solid #70d6ed;cursor:crosshair}
@keyframes cell-mark-pulse{0%{background:#a6efff70;box-shadow:inset 0 0 18px #a6efff90,0 0 12px #70d6ed88}100%{background:#70d6ed20;box-shadow:inset 0 0 10px #70d6ed33,0 0 5px #70d6ed33}}
@media(prefers-reduced-motion:reduce){.reference-cell.just-marked{animation:none}}