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

body {
  background: linear-gradient(to right, #189999, #205757);
}

.calculator {
  max-width: 375px;
  margin: 100px auto 0;
  background: #222222;
  border-radius: 25px;
  padding: 30px;
  color: #f1f1f1;
  box-shadow: 0 5px 10px rgba(0,0,0,0.3);
}
.display {
  font-weight: 200;
  padding: 60px 15px;
  margin-bottom: 25px;
  border-radius: 25px;
  border: 1px solid rgb(97,97,97);
  background: #2a3636;
  position: relative;
  overflow: hidden;
  box-shadow: 
  inset 0 5px 8px #191919,
  inset 0 -1px 6px #06121d;
}

.calculation,
.result {
  position: absolute;
  right: 20px;
}
.calculation {
  font-family: Open sans, sans-serif;
  font-size: 18px;
  font-weight: 100;
  top: 20px;
}
.result {
  bottom: 10px;
  font-family: Roboto, sans-serif;
  font-size: 30px;
  font-weight: 700;
  margin-top: 5px;
}
.grid {
  display: grid;
  grid-template-columns: repeat(4, 1fr);
  grid-auto-rows: 60px;
  grid-gap: 20px;
}
.grid button {
  font-family: Open sans, sans-serif;
  border: none;
  font-size: 22px;
  color: #f1f1f1;
  font-weight: 100;
  cursor: pointer;
  border-radius: 10px;
  background: #222222;
  box-shadow: 0 4px 8px #000000,
  0px -1px 6px #41484e;
}

button[data-action="c"] {
  grid-column: span 2;
}

button[data-action="="] {
  grid-column: span 2;
  font-weight: 400;
  font-size: 30px;
  color: #101a22;
  background: #189999;
}