*,
*::before,
*::after {
  box-sizing: border-box;
  font-family: 'Nova Mono', 'VT323', monospace;
  font-weight: normal;
}

body {
  background: linear-gradient(to right, #314755, #26a0da);
  padding: 0;
  margin: 0;
}

footer {
  text-align: center;
  color: #ffffff;
}

.calculator-grid {
  display: grid;
  grid-template-columns: repeat(4, 75px);
  grid-template-rows: minmax(120px, auto) repeat(5, 75px);
  min-height: 90vh;
  justify-content: center;
  align-content: center;
}
@media (min-width: 768px) {
  .calculator-grid {
    grid-template-columns: repeat(4, 100px);
    grid-template-rows: minmax(120px, auto) repeat(5, 100px);
  }
}

.output {
  grid-column: 1 / -1;
  background-color: rgba(0, 0, 0, 0.75);
  display: flex;
  align-items: flex-end;
  flex-direction: column;
  justify-content: space-around;
  word-break: break-all;
  word-wrap: break-word;
  padding: 10px;
}

.previous-operand {
  color: rgba(255, 255, 255, 0.75);
  font-size: 1.5rem;
}

.current-operand {
  color: rgba(255, 255, 255, 0.9);
  font-size: 2.5rem;
}

.calculator-grid > button {
  background-color: rgba(255, 255, 255, 0.75);
  font-size: 1.5rem;
  border: 1px solid white;
  outline: none;
}

.calculator-grid > button:hover {
  cursor: pointer;
  background-color: rgba(255, 255, 255, 0.9);
}

.span-two {
  grid-column: span 2;
}

.calculator-grid > .red {
  background-color: rgba(222, 57, 22, 0.9);
}
.calculator-grid > .red:hover {
  cursor: pointer;
  background-color: rgba(222, 57, 22, 0.75);
}