@import url("https://fonts.googleapis.com/css2?family=Open+Sans&display=swap");
#body {
  background-color: grey;
}
.calculator {
  padding: 10px;
  border-radius: 1em;
  height: 380px;
  width: 400px;
  margin: auto;
  background-color: #191b28;
  box-shadow: rgba(0, 0, 0, 0.19) 0px 10px 20px, rgba(0, 0, 0, 0.23) 0px 6px 6px;
}
.display-box {
  font-family: "Open Sans", sans-serif;
  background-color: #dcdbe1;
  border: solid black 0.5px;
  color: black;
  border-radius: 5px;
  width: 98%;
  height: 110%;
}

#btn {
  background-color: rgb(0, 135, 88);
}
input[type="button"] {
  font-family: "Open Sans", sans-serif;
  background-color: rgb(0, 135, 88);
  color: white;
  border: solid black 0.5px;
  width: 100%;
  height: 70%;
  border-radius: 5px;
  outline: none;
}
input:active[type="button"] {
  background: #e5e5e5;
}
.backbtn {
  position: relative;
  left: 10px;
  color: black;
}