body {
    font-family: Arial, sans-serif;
    background-color: #f2f2f2; }

.calculadora {
    background-color: #6b7c93;
    color: white;
    width: 280px;
    margin: 90px auto;
    padding: 10px;
    border-radius: 10px;
    box-shadow: 0 0 20px rgba(0, 0, 0, 0.5); }

.pantalla {
    background-color: #4f5b6e;
    padding: 10px;
    font-size: 2em;
    text-align: right;
    border-radius: 5px;
    margin-bottom: 10px;
    box-shadow: inset 0 -1px 5px rgba(255, 255, 255, 0.2); }

.botones {
    display: grid;
    grid-template-columns: repeat(4, 1fr);
    grid-gap: 10px;
    margin-top: 10px; }

button {
    font-size: 1.5em;
    width: 60px;
    height: 60px;
    border-radius: 5px;
    border: none;
    box-shadow: 0 0 5px rgba(0, 0, 0, 0.3);
    background-color: #e0e0e0;
    color: #333;
    cursor: pointer;
    transition: background-color 0.3s ease; }

.operacion {
    background-color: #ff9900;
    color: white; }

.igual {
    background-color: #4CAF50;
    color: white;
    width: 445%; }

#boton {
    background-color: #ff3300;
    color: white; }

button:hover {
    background-color: #ddd; }