<a class="btn"><span>Go to Home</span><em></em></a>

* {
  margin: 0;
  padding: 0;
}
html, body {
  height: 100%;
  background: #006b62;
  position: relative;
}
.btn {
  cursor: pointer;
  background-color: #000;
  width: 330px;
  height: 64px;
  line-height: 64px;
  position: absolute;
  left: 50%;
  top: 50%;
  transform: translate(-50%, -50%);
  z-index: 0;
  box-shadow: 0px 0px 17px 1px rgba(0, 0, 0, 0.34);
  span {
    color: #fff;
    display: block;
    padding-left: 35px;
    text-transform: uppercase;
    font: bold 18px/66px Arial;
    transform: scaleX(0.6);
    letter-spacing: 3px;
    transform-origin: center left;
    transition: color 0.3s ease;
    position: relative;
    z-index: 1;
  }
  em {
    position: absolute;
    height: 1px;
    background: #fff;
    width: 47%;
    right: 23px;
    top: 50%;
    transform: scaleX(0.25);
    transform-origin: center right;
    transition: all 0.3s ease;
    z-index: 1;
  }
  &:before, &:after {
    content: '';
    background: #fff;
    height: 50%;
    width: 0;
    position: absolute;
    transition: .3s cubic-bezier(.785,.135,.15,.86);
  }
  &:before {
    top: 0;
    left: 0;
    right: auto;
  }
  &:after {
    bottom: 0;
    right: 0;
    left: auto;
  }
  &:hover {
    &:before {
      width: 100%;
      right: 0;
      left: auto;
    }
    &:after {
      width: 100%;
      left: 0;
      right: auto;
    }
    span {
      color: #000;
    }
    em {
      background: #000;
      transform: scaleX(1);
    }
  }
}