SemanSemantic-UItic-UI/build/minified/modules/tab.min.css

.ui.tab {
  display: none;
}

.ui.tab.active,
.ui.tab.open {
  display: block;
}

.ui.tab.loading {
  position: relative;
  overflow: hidden;
  display: block;
  min-height: 250px;
  text-indent: -10000px;
}

.ui.tab.loading * {
  position: relative!important;
  left: -10000px!important;
}

.ui.tab.loading:after {
  position: absolute;
  top: 50px;
  left: 50%;
  content: 'Loading...';
  margin-left: -32px;
  text-indent: 5px;
  color: rgba(0,0,0,.4);
  width: 100%;
  height: 100%;
  padding-top: 75px;
  background: url(../images/loader-large.gif) no-repeat 0 0;
  visibility: visible;
}