blue-twilight/resources/sass/tether.scss

.tether-element, .tether-element:after, .tether-element:before, .tether-element *, .tether-element *:after, .tether-element *:before {
  box-sizing: border-box; }

.tether-element {
  position: absolute;
  display: none; }
  .tether-element.tether-open {
    display: block; }