elm-spa/example/public/main.css

.fixed--full {
  position: fixed;
  top: 0;
  left: 0;
  right: 0;
  bottom: 0;
}

.absolute--full {
  position: absolute;
  top: 0;
  left: 0;
  right: 0;
  bottom: 0;
}

.absolute--center {
  position: fixed;
  top: 50%;
  left: 50%;
  transform: translate(-50%, -50%);
}

.bg--overlay {
  background: rgba(0,0,0,0.25);
}
.min-width--480 {
  min-width: 320px;
}
.bg--white {
  background: white;
}