body {
  font-size: 10vh;
  background-color: black;
}

button {
  font-size: 4vh;
}

.background-green {
  background: green;
  background-color: green;
}

.calculator {
  display: grid;
  height: 87.5vh;
  width: 50vh;
  margin: auto;
  justify-content: center;
  grid-template-columns: 1fr 1fr 1fr 1fr;
  grid-template-rows: auto auto;
  grid-template-areas:
    "header header header header"
    "main main main main"
    "main main main main"
    "main main main main"
    "main main main main"
    "main main main main";
}

.item-header {
  grid-area: header;
  color: white;
}

#currentValue {
  background-color: black;
  grid-column-start: 1;
  grid-column-end: span 4;
  text-align: right;
}

button.btn {
  background-color: dimgray;
  border: none;
  color: white;
  padding: 3vh;
  text-align: center;
  margin: 0.6vh 0.3vh;
  border-radius: 50%;
}

button.orange {
  background-color: orange;
}

button.orange:focus {
  background-color: white;
  color: gold;
}

button.silver {
  background-color: silver;
  color: black;
}

button.silver:focus {
  background-color: white;
  color: black;
}

button.equals {
  background-color: orange;
}

button.equals:focus {
  background-color: white;
  color: gold;
}

button.equals {
  text-align: center;
  padding-left: 5vh;
  padding-right: 5vh;
  grid-row: 7;
  grid-column-start: 1;
  grid-column-end: span 4;
  border-radius: 6.25vh;
}