.day.volli{
  position: relative;
background: var(--tbl-main-tr3);
}

.day.volli::after{
  content: "●";
  color: var(--akzent-red-soft);
  position: absolute;
  top: 2px;
  right: 5px;
  font-size: var(--txtxxsmall);
  line-height: 1;
  filter: drop-shadow(0 1px 2px rgba(0,0,0,.6));
}