:root {
  --color-fondo: #232323;
  --color-calculadora: #48bfff;
  --color-pantalla: #090c31;
  --color-boton: #006da7;
  --color-boton-hover: #004f78;
  --color-igual: #e65766;
  --color-igual-hover: #e6394a;
  --color-texto: #ffffff;
}

* {
  margin: 0;
  padding: 0;
  box-sizing: border-box;
  font-family: sans-serif;
}

body {
  min-height: 100vh;
  background-color: var(--color-fondo);
  display: grid;
  place-items: center;
}

.calculadora {
  background-color: var(--color-calculadora);
  color: var(--color-texto);
  width: 350px;
  max-width: 100%;
  padding: 1.5rem;
  border-radius: 1.5rem;
  display: grid;
  grid-template-columns: repeat(4, 1fr);
  gap: .5rem;
  box-shadow: 0 0 20px var(--color-calculadora);
}

.pantalla {
  grid-column: 1 / 5;
  background-color: var(--color-pantalla);
  padding: 1.5rem;
  font-size: 2rem;
  text-align: right;
  border-radius: .5rem;
  margin-bottom: 1.5rem;
  font-family: monospace;
  font-weight: bold;
  overflow: hidden;
  white-space: nowrap;
}

.btn {
  background-color: var(--color-boton);
  color: var(--color-texto);
  border: none;
  padding: 1.5rem .5rem;
  display: flex;
  justify-content: center;
  align-items: center;
  border-radius: .5rem;
  cursor: pointer;
  font-size: 1.2rem;
  transition: background-color 0.3s ease;
}

.btn:hover {
  background-color: var(--color-boton-hover);
}

#cero {
  grid-column: span 2;
}

#igual {
  grid-row: span 2;
  background-color: var(--color-igual);
}

#igual:hover {
  background-color: var(--color-igual-hover);
}