html {
  font-size: 62.5%;
  box-sizing: border-box;
}

*, *::before, *::after {
  margin: 0;
  padding: 0;
  box-sizing: inherit;
}

body {
  background-color: #EBEBF5;
}

.calculator {
  width: 375px;
  margin: 2rem auto;
  background: #F6F8F9;
  border-radius: 26px;
  padding: 36px 28px;
  box-shadow: 0px 0px 30px 0px rgb(33 30 25 / 10%);
}

.calculator-screen {
  background-color: transparent;
  width: 100%;
  font-size: 5rem;
  height: 80px;
  border: none;
  color: #202020;
  text-align: right;
  padding-right: 20px;
  padding-left: 10px;
}

button {
  border: 0;
  display: flex;
  justify-content: center;
  align-items: center;
  background: #E9F0F4;
  font-size: 2.4em;
  line-height: 2.4em;
  border-radius: 20px;
  width: 100%;
  cursor: pointer;
  -webkit-tap-highlight-color: transparent;
  transition: .2s;
}

button:hover {
  opacity: .8;
}

button:focus {
  outline: 0;
}

.operator {
  background: #FF9500;
  color: #ffffff;
}

.all-clear {
  background: #F8ECED;
  color: #F64D56;
}

.equal-sign {
  background: #31C973;
  color: #ffffff;
  height: 100%;
  grid-area: 2 / 4 / 6 / 5;
}

.equal-sign:hover {
  background-color: #4e9ed4;
}

.calculator-keys {
  display: grid;
  grid-template-columns: repeat(4, 1fr);
  grid-gap: 14px;
  padding: 20px;
}