* {
  padding: 0;
  margin: 0;
}

body {
  background: #34495e;
}

main {
  position: absolute;
  left: 50%;
  top: 50%;
  transform: translate(-50%, -50%);
}

main .btn {
  display: block;
  height: 30px;
  width: 150px;
  border: solid 2px #e74c3c;
  background: none;
  color: white;
  position: relative;
  text-align: center;
  display: flex;
  justify-content: center;
  align-items: center;
  overflow: hidden;
  cursor: pointer;
  box-shadow: 0 3px 8px rgba(0, 0, 0, .3);
}

main .btn::before {
  transition: all .8s;
  align-self: center;
  content: '';
  position: absolute;
  width: 0;
  height: 100%;
  background: #e74c3c;
  z-index: -1;
  transform: skewX(-45deg);
}

main .btn:hover::before {
  width: 200%;
}