.b_container {
  position: relative;
  top: 50%;
  left: 50%;
  transform: translate(-50%, -50%);
}

.b_wrapper {
  position: fixed;
  top: 50%;
  left: 50%;
  transform: translate(-50%, -50%);
}

.b_link_wrapper {
  position: relative;
}

a.custom_button {
  font-family: 'Lato', sans-serif;
  display: block;
  width: 250px;
  height: 50px;
  line-height: 50px;
  font-weight: bold;
  text-decoration: none;
  background: #333;
  text-align: center;
  color: #fbfffa;
  text-transform: uppercase;
  letter-spacing: 1px;
  border: 3px solid #333;
  transition: all .35s;
}

.b_icon {
  width: 50px;
  height: 50px;
  border: 3px solid transparent;
  position: absolute;
  transform: rotate(45deg);
  right: 0;
  top: 0;
  z-index: -1;
  transition: all .35s;
}

.b_icon svg {
  width: 30px;
  position: absolute;
  top: calc(50% - 15px);
  left: calc(50% - 15px);
  transform: rotate(-45deg);
  fill: #2ecc71;
  transition: all .35s;
}

a.custom_button:hover {
  width: 200px;
  border: 3px solid #2ecc71;
  background: transparent;
  color: #2ecc71;
}

a.custom_button:hover + .b_icon {
  border: 3px solid #2ecc71;
  right: -25%;
}