/* Виртуальный контроллер */

.btnflip 
{
  position: absolute;
  top: 6.4%;
  left: 57%;
  transform: translate(-50%, -50%);
  height: 10%; 
  width:calc( ( 200vw - 480px ) / ( 1920 - 480 ) * ( 160 - 8 ) + 8px );
  text-align: center;
  transform-style: preserve-3d;
  perspective: 1000px;
  transform-origin: center center;
}
.btnflip-item 
{
  position: absolute;
  top: 0;
  left: 0;
  width: 100%;
  height: 100%;
  line-height: 280%;
  font-size:calc( ( 100vw - 480px ) / ( 1920 - 480 ) * ( 32 - 10 ) + 10px );
  background-color: rgba(255,255,255, .05);
  transform-style: preserve-3d;
  backface-visibility: hidden;
  border-radius: 18%;
  text-transform: uppercase;
  color: #fff;
  transition: 1s;
}
.btnflip-item.btnflip__front 
{
  transform: rotateX(0deg) translateZ(20px);
}
.btnflip:hover .btnflip-item.btnflip__front 
{
  transform: rotateX(-180deg) translateZ(20px);
}
.btnflip-item.btnflip__back {
  transform: rotateX(180deg) translateZ(20px);
}
.btnflip:hover .btnflip-item.btnflip__back 
{
  transform: rotateX(0deg) translateZ(20px);
}
.btnflip-item.btnflip__center 
{
  background: linear-gradient(to left, DimGrey, Gainsboro);
}
.btnflip-item.btnflip__center::before 
{
  content: '';
  position: absolute;
  top: 0;
  left: 0;
  width: 100%;
  height: 100%;
  background: linear-gradient(to left, #ffdd1f, #c31a5b);
  border-radius: 19%;
  transform: translateZ(-1px);
}
.btnflip:hover .btnflip-item.btnflip__center 
{
  transform: rotateX(-180deg);
}