.btn{
  border: 1px solid rgb(255, 255, 255);
  background: none;
  padding: 7px 8px;
  font-size: 1rem;
  cursor: pointer;
  transition: 0.8s;
  overflow:hidden ;
  position: relative;
}

.btn1{
  color: rgb(255, 255, 255);
}

.btn1:hover{
  color: rgb(0, 1, 66);
}

.btn::before{
  content: "";
  position: absolute;
  left: 0;
  width: 150%;
  height: 0%;
  background:rgb(255, 255, 255);
  z-index: -1;
  transition: 0.7s;
}

.btn1::before{
  top: 0;
  border-radius: 0 0 50% 50%;
}

.btn1:hover::before{
  height: 180%;
}