dat.gui/elements/gui-button/gui-button.css

#container {
  height: 100%;
  cursor: pointer;
}
#button {
  width: 21px;
  height: 21px;
  -webkit-box-sizing: border-box;
  -moz-box-sizing: border-box;
  box-sizing: border-box;
  border-radius: 0;
  padding: 4px 0px;
  position: relative;
  background: transparent;
  margin: 0 auto;
}
#button.open-true .one {
  -webkit-transform: translate3d(4px, 0, 0) rotate(45deg) translate3d(3.5px, 0, 0);
  -moz-transform: translate3d(4px, 0, 0) rotate(45deg) translate3d(3.5px, 0, 0);
  -o-transform: translate3d(4px, 0, 0) rotate(45deg) translate3d(3.5px, 0, 0);
  -ms-transform: translate3d(4px, 0, 0) rotate(45deg) translate3d(3.5px, 0, 0);
  transform: translate3d(4px, 0, 0) rotate(45deg) translate3d(3.5px, 0, 0);
  width: 11px;
}
#button.open-true .three {
  -webkit-transform: translate3d(4px, 0, 0) rotate(-45deg) translate3d(3.5px, 0, 0);
  -moz-transform: translate3d(4px, 0, 0) rotate(-45deg) translate3d(3.5px, 0, 0);
  -o-transform: translate3d(4px, 0, 0) rotate(-45deg) translate3d(3.5px, 0, 0);
  -ms-transform: translate3d(4px, 0, 0) rotate(-45deg) translate3d(3.5px, 0, 0);
  transform: translate3d(4px, 0, 0) rotate(-45deg) translate3d(3.5px, 0, 0);
  width: 11px;
}
#button.open-true .two {
  width: 0;
}
#button.open-true .slider:before {
  width: 0;
  height: 0;
}
.slider {
  width: 21px;
  border-radius: 2px;
  height: 1px;
  background: #ecebe0;
  position: absolute;
  -webkit-transform-origin: 0.5px 0.5px;
  -moz-transform-origin: 0.5px 0.5px;
  -o-transform-origin: 0.5px 0.5px;
  -ms-transform-origin: 0.5px 0.5px;
  transform-origin: 0.5px 0.5px;
  -webkit-transition: all 200ms 200ms cubic-bezier(0, 0.5, 0, 1);
  -moz-transition: all 200ms 200ms cubic-bezier(0, 0.5, 0, 1);
  -o-transition: all 200ms 200ms cubic-bezier(0, 0.5, 0, 1);
  -ms-transition: all 200ms 200ms cubic-bezier(0, 0.5, 0, 1);
  transition: all 200ms 200ms cubic-bezier(0, 0.5, 0, 1);
}
.slider:before {
  width: 5px;
  height: 5px;
  margin-top: -2px;
  margin-left: -2.5px;
  border-radius: 5px;
  background: #ecebe0;
  display: inline-block;
  content: ' ';
  position: absolute;
  left: 70%;
  -webkit-transition: left 200ms cubic-bezier(0, 0.5, 0, 1), width 0.001s 200ms, height 0.001s 200ms;
  -moz-transition: left 200ms cubic-bezier(0, 0.5, 0, 1), width 0.001s 200ms, height 0.001s 200ms;
  -o-transition: left 200ms cubic-bezier(0, 0.5, 0, 1), width 0.001s 200ms, height 0.001s 200ms;
  -ms-transition: left 200ms cubic-bezier(0, 0.5, 0, 1), width 0.001s 200ms, height 0.001s 200ms;
  transition: left 200ms cubic-bezier(0, 0.5, 0, 1), width 0.001s 200ms, height 0.001s 200ms;
}
.slider.two {
  margin-top: 6px;
}
.slider.two:before {
  left: 30%;
  -webkit-transition-delay: 0ms, 200ms, 200ms;
  -moz-transition-delay: 0ms, 200ms, 200ms;
  -o-transition-delay: 0ms, 200ms, 200ms;
  -ms-transition-delay: 0ms, 200ms, 200ms;
  transition-delay: 0ms, 200ms, 200ms;
}
.slider.three {
  margin-top: 12px;
}
.slider.three:before {
  left: 70%;
  -webkit-transition-delay: 0ms, 200ms, 200ms;
  -moz-transition-delay: 0ms, 200ms, 200ms;
  -o-transition-delay: 0ms, 200ms, 200ms;
  -ms-transition-delay: 0ms, 200ms, 200ms;
  transition-delay: 0ms, 200ms, 200ms;
}