foundry/Data/modules/wall-height/styles/wall-height.css

#wall-height-tooltip {
  grid-template-columns: 40% 60%;
  grid-auto-rows: auto;
  justify-items: start;
  align-content: start;
  justify-content: start;
  padding: 3px 0;
  color: #f1f1f1;
  border: 2px solid;
  border-radius: 5px;
  background-color:rgba(0, 0, 0, 0.6);
}
#wall-height-tooltip span {
  padding: 0 3px;
  text-align: left;
}