.button {
  width: 150px;
  height: 50px;
  border-radius: 50px;
  background-color: transparent;
  border: 2px solid #000814;
  overflow: hidden;
  position: relative;
  font-size: 16px;
  font-weight: 500;
  text-transform: uppercase;
  transition: 300ms ease;
}

.button::before {
  content: "";
  position: absolute;
  z-index: -1;
  width: 150px;
  height: 150px;
  border-radius: 50%;
  background-color: #003566;
  top: 100%;
  left: 0;
  transition: 500ms ease;
}

.button:hover {
  color: #fff;
  letter-spacing: 3px;
}

.button:hover::before {
  top: 50%;
  left: 50%;
  transform: translate(-50%, -50%);
}