$buttonBaseColor: #336699;
$disableDuration: 2s;
button.cooldown{
  background: $buttonBaseColor;
  min-height: 48px;
  min-width: 144px;
  position: relative;
  margin: 5px;
  border-radius: 5px;
  border: 0;
  color: #fff;
  padding: 0 15px;
  font-size: 16px;
  outline: none;
  overflow: hidden;
  cursor: pointer;
  &:active, &:focus{
    outline: none;
  }
  &:disabled{
    background: darken($buttonBaseColor, 10%);
    color: darken(#fff, 15%);
    cursor: default;
    box-shadow: inset 3px 3px 10px 0px rgba(0,0,0,0.2);
    &:after{
      content: '';
      position: absolute;
      bottom: 0;
      width: 100%;
      left: 0;
      height: 5px;
      background: darken($buttonBaseColor, 20%);
      animation: cooldown $disableDuration linear;
    }
  }
}

@keyframes cooldown {
   0% { width: 100%; }
   100% { width: 0; }
}