MediaWiki:Common.css

/* CSS placed here will be applied to all skins */

/* Four-part reference for margin, padding, etc. is: top, right, bottom, left */

div.box {
  border: 1px solid gray;
  padding: 5px;
  margin: 5px;
  background-color: black;
}

div.box-contents {
  filter: invert(1);
}