form {
  padding: 30px;
  width: 268px;
  background-color: slategray;
  display: flex;
  flex-direction: column;
  align-items: center;
  justify-content: center;
  border-radius: 20px;
  -webkit-box-shadow: 0px 0px 0px 5px #a0a0a0, inset 0px 10px 27px -8px #141414,
    inset 0px -10px 27px -8px rgb(188, 201, 214),
    5px 5px 15px 5px rgba(0, 0, 0, 0);
  box-shadow: 0px 0px 0px 5px #a0a0a0, inset 0px 10px 27px -8px #141414,
    inset 0px -10px 27px -8px rgb(188, 201, 214),
    5px 5px 15px 5px rgba(0, 0, 0, 0);
}

.display {
  width: 238px;
  height: 40px;
  font-size: 22px;
  margin-bottom: 30px;
  text-align: right;
}

.btn {
  width: 46px;
  height: 46px;
  cursor: pointer;
  color: azure;
  background-color: darkslategray;
  margin: 0;
  font-weight: bold;
}