.button_base {
  margin: 0;
  border: 0;
  font-size: 18px;
  position: relative;
  top: 50%;
  left: 50%;
  margin-top: -25px;
  margin-left: -100px;
  width: 200px;
  height: 50px;
  text-align: center;
  box-sizing: border-box;
  -webkit-box-sizing: border-box;
  -moz-box-sizing: border-box;
  cursor: default;
}

.button_base:hover {
  cursor: pointer;
}

.b_3d {
  perspective: 500px;
  -webkit-perspective: 500px;
  -moz-perspective: 500px;
  transform-style: preserve-3d;
  -webkit-transform-style: preserve-3d;
}

.b_3d div {
  position: absolute;
  text-align: center;
  padding: 10px;
  border: #000000 solid 1px;
  pointer-events: none;
  box-sizing: border-box;
  -webkit-box-sizing: border-box;
  -moz-box-sizing: border-box;
}

.b_3d div:nth-child(1) {
  color: #ffffff;
  background-color: #7c00fe;
  z-index: 0;
  width: 100%;
  height: 50px;
  clip: rect(0px, 100px, 50px, 0px);
  position: absolute;
  transition: all 0.2s ease;
  -webkit-transition: all 0.2s ease;
  -moz-transition: all 0.2s ease;
  transform: rotateX(0deg);
  -webkit-transform: rotateX(0deg);
  -moz-transform: rotateX(0deg);
  transform-origin: 50% 50% -25px;
  -webkit-transform-origin: 50% 50% -25px;
  -moz-transform-origin: 50% 50% -25px;
}

.b_3d div:nth-child(2) {
  color: #000000;
  background-color: #f9e400;
  z-index: -1;
  width: 100%;
  height: 50px;
  clip: rect(0px, 100px, 50px, 0px);
  position: absolute;
  transform: rotateX(90deg);
  -webkit-transform: rotateX(90deg);
  -moz-transform: rotateX(90deg);
  transition: all 0.2s ease;
  -webkit-transition: all 0.2s ease;
  -moz-transition: all 0.2s ease;
  transform-origin: 50% 50% -25px;
  -webkit-transform-origin: 50% 50% -25px;
  -moz-transform-origin: 50% 50% -25px;
}

.b_3d div:nth-child(3) {
  color: #000000;
  background-color: #f9e400;
  z-index: 0;
  width: 100%;
  height: 50px;
  clip: rect(0px, 200px, 50px, 100px);
  position: absolute;
  transition: all 0.2s ease 0.1s;
  -webkit-transition: all 0.2s ease 0.1s;
  -moz-transition: all 0.2s ease 0.1s;
  transform: rotateX(0deg);
  -webkit-transform: rotateX(0deg);
  -moz-transform: rotateX(0deg);
  transform-origin: 50% 50% -25px;
  -webkit-transform-origin: 50% 50% -25px;
  -moz-transform-origin: 50% 50% -25px;
}

.b_3d div:nth-child(4) {
  color: #ffffff;
  background-color: #7c00fe;
  z-index: -1;
  width: 100%;
  height: 50px;
  clip: rect(0px, 200px, 50px, 100px);
  position: absolute;
  transform: rotateX(-90deg);
  -webkit-transform: rotateX(-90deg);
  -moz-transform: rotateX(-90deg);
  transition: all 0.2s ease 0.1s;
  -webkit-transition: all 0.2s ease 0.1s;
  -moz-transition: all 0.2s ease 0.1s;
  transform-origin: 50% 50% -25px;
  -webkit-transform-origin: 50% 50% -25px;
  -moz-transform-origin: 50% 50% -25px;
}

.b_3d:hover div:nth-child(1) {
  background-color: #7c00fe;
  transition: all 0.2s ease;
  -webkit-transition: all 0.2s ease;
  -moz-transition: all 0.2s ease;
  transform: rotateX(-90deg);
  -webkit-transform: rotateX(-90deg);
  -moz-transform: rotateX(-90deg);
}

.b_3d:hover div:nth-child(2) {
  color: #000000;
  transition: all 0.2s ease;
  -webkit-transition: all 0.2s ease;
  -moz-transition: all 0.2s ease;
  transform: rotateX(0deg);
  -webkit-transform: rotateX(0deg);
  -moz-transform: rotateX(0deg);
}

.b_3d:hover div:nth-child(3) {
  background-color: #f9e400;
  transition: all 0.2s ease 0.1s;
  -webkit-transition: all 0.2s ease 0.1s;
  -moz-transition: all 0.2s ease 0.1s;
  transform: rotateX(90deg);
  -webkit-transform: rotateX(90deg);
  -moz-transform: rotateX(90deg);
}

.b_3d:hover div:nth-child(4) {
  color: #ffffff;
  transition: all 0.2s ease 0.1s;
  -webkit-transition: all 0.2s ease 0.1s;
  -moz-transition: all 0.2s ease 0.1s;
  transform: rotateX(0deg);
  -webkit-transform: rotateX(0deg);
  -moz-transform: rotateX(0deg);
}

.back {
  height: 200px;
  float: left;
  box-sizing: border-box;
  -webkit-box-sizing: border-box;
  -moz-box-sizing: border-box;
  counter-increment: bc;
  padding: 0px 5px 5px 5px;
}