body {
  margin: 0;
  display: flex;
  justify-content: center;
  align-items: center;
  height: 100vh;
  background-color: hsl(0, 0%, 95%);
}
#calculator {
  font-family: Arial, Helvetica, sans-serif;
  background-color: hsl(0, 0%, 15%);
  border-radius: 3%;
  max-width: 32rem;
  overflow: hidden;
}
#display {
  width: 1px;

  padding: 20px;
  display: block;
  font-size: 4rem;
  height: 4rem;
  width: 90%;
  /* width: auto; */
  text-align: right;
  margin-left: 3px;
  margin-top: 3px;

  /* border:2px solid red; */
  border-radius: 15px;
  background-color: hsl(0, 0%, 20%);
  color: white;
  /* margin: 0 54rem 0 0; */
}
#keys {
  display: grid;
  grid-template-columns: repeat(4, 1fr);
  gap: 10px;
  padding: 25px;
}

button {
  height: 5rem;
  width: 5rem;
  border-radius: 50%;
  border: none;
  background-color: hsl(0, 0%, 30%);
  font-size: 3rem;
  color: white;
  font-weight: 400;
  cursor: pointer;
}
button:hover {
  background-color: hsl(0, 0%, 40%);
}
button:active {
  background-color: hsl(0, 0%, 50%);
}
.operator-btn {
  background-color: hsl(35, 100%, 55%);
}
.operator-btn:hover {
  background-color: hsl(35, 100%, 65%);
}
.operator-btn:active {
  background-color: hsl(35, 100%, 75%);
}