* {
  padding: 0;
  margin: 0;
  box-sizing: border-box;
}

html {
  font-size: 62.5%;
}

body {
  box-sizing: inherit;
  font-family: "Inter", ui-sans-serif, system-ui, sans-serif, "Apple Color Emoji", "Segoe UI Emoji", "Segoe UI Symbol", "Noto Color Emoji";
  color: #fff;
  background-color: rgba(26, 26, 26, 1);
}

main {
  height: 93vh;
  display: flex;
  justify-content: center;
  align-items: center;
}
.calculator {
  color: #fff;
  height: 48rem;
  width: 32rem;
  /* box-shadow: 0 0 7rem #75b816b3; */
  border: 1px solid #406809;
  transition: all 0.5s;
  border-radius: 0.5rem;
  display: flex;
  flex-direction: column;
  justify-content: space-between;
  padding: 2rem 2rem;
  padding-bottom: 4rem;
  gap: 2rem;
}

.calculator:hover,
.calculator:active {
  box-shadow: 0 0 9rem #75b8164f;
  border: 1px solid #75b8164f;
}

#display {
  color: #fff;
  height: 11rem;
  outline: none;
  border-radius: 0.5rem;
  border: 0.5px solid #53850c;
  cursor: text;
  padding: 3rem 2rem;
  font-size: 4rem;
  text-align: end;
  background: none;
  background-color: #1a1a1a;
}

.keys {
  display: grid;
  grid-template-columns: repeat(4, 6.4rem);
  row-gap: 0.9rem;
  justify-content: space-between;
}

.calculator-btn {
  color: #fff;
  height: 5rem;
  background-color: #1a1a1a;
  border: 1px solid grey;
  border-radius: 0.5rem;
  transition: all 0.2s;
  cursor: pointer;
}

.calculator-btn:hover {
  background-color: #313131;
}

.calculator-btn:active {
  transform: scale(0.97);
}

.equal {
  grid-column: 3 / 5;
  color: #fff;
  background-color: #2e4a07;
  border: 1px solid #2e4a07;
  transition: all 0.2s;
}

.btn-operation {
  color: #7da93d;
  border: 1px solid #406809;
}

.equal:hover {
  background-color: #4b6525;
}