html {
  font-size: 10px;
}
body {
  margin: 0;
  padding: 0;
}
.btn-succes {
  position: relative;
  top: 200px;
  left: 50%;
  transform: translateX(-50%);
  background: yellow;
  width: 200px auto;
  height: 200px;
}
.cross {
  display: block;
  width: 20px;
  height: 20px;
}