View source for MediaWiki:Inventory slot.css

.inventory {
  border-collapse: collapse;
  background: #3c3f41;
}

/* single slot */
.invslot {
  width: 32px;
  height: 32px;
  display: inline-block;
  vertical-align: top;
  background: #8b8b8b;
  border: 1px solid #000;
  position: relative;
  margin: 1px;
  overflow: visible;
}

.slotwrap,
.invslot > a.image {
  display: block;
  width: 32px;
  height: 32px;
  line-height: 0;
}

.invslot img,
.invslot > a.image img {
  display: block;
  width: 32px;
  height: 32px;
}

/* bottom right number */
.invslot .invcount {
  position: absolute;
  bottom: 0;
  right: 1px;
  color: #fff;
  text-shadow: 0 1px 0 #000;
  font-weight: bold;
  font-size: 8px;
  line-height: 8px;
}

/* tooltip */
.mctt {
  position: absolute;
  top: -46px;
  left: 50%;
  transform: translateX(-50%);
  background: rgba(16, 0, 16, 0.95);
  border: 1px solid #000;
  padding: 4px 6px;
  color: #fff;
  font-family: monospace;
  font-size: 10px;
  white-space: nowrap;
  pointer-events: none;
  z-index: 9999;
  display: none;
  box-shadow: 2px 2px 0 #000;
}

/* show tooltip on hover */
.invslot:hover .mctt {
  display: block;
}

/* white overlay on hover */
.invslot::after {
  content: "";
  position: absolute;
  inset: 0;
  background: rgba(255, 255, 255, 0.25);
  opacity: 0;
  transition: opacity 0.1s ease-in-out;
  pointer-events: none;
}

.invslot:hover::after {
  opacity: 1;
}