.calculator {
  margin: 50px auto;
  padding: 18px;
  width: 300px;
  height: 500px;
  background-color: #000000;
  border-radius: 20px;
  color: #FFFFFF;
  font-family: Arial;
  box-shadow: 4px 4px 4px #3D3E42
  
}

.screen {
  text-align: right;
  user-select: none;
  line-height: 10px;
  font-size: 60px;

}

.buttons {
  display: grid;
  grid-template-columns: repeat(4, 70px);
  grid-template-rows: repeat(4, 70px);
  grid-gap: 7px;
  justify-items: center;
}
.btn {
  width: 60px;
  height: 60px;
  background-color:#3D3E42;
  border-radius: 50%;
  text-align: center;
  line-height: 60px;
  user-select: none;
  font-size: 1.5rem;
}

.btn:hover {
  filter: brightness(120%)
}

.btn:active {
  filter: brightness(50%)
}

.bg-orange {
  background-color: #F37D0D
}

.bg-grey {
  background-color: #B4B0AC
}

.zero {
  grid-column: 1/3;
  width:100%;
  border-radius: 34px;
}