.calculadora {
    width: 350px;
    margin: 40px auto;
    padding: 20px;
    border: 2px solid #aaa;
    border-radius: 10px;
    background: #f9f9f9;
}
input[type="text"] {
    width: 95%;
    font-size: 1.2em;
    margin-bottom: 10px;
    padding: 5px;
}
.grande {
    font-size: 1.1em;
    color: #333;
    margin-bottom: 10px;
}
.botones button {
    margin: 4px 2px;
    padding: 8px 12px;
    font-size: 1em;
    border-radius: 5px;
    border: 1px solid #888;
    background: #e0e0e0;
    cursor: pointer;
}
.botones hr {
    margin: 10px 0;
    border: none;
    border-top: 1px solid #bbb;
}

/* Estilo para el encabezado h1 */
h1 {
    text-align: center;
    color: #2c3e50;
    font-size: 2em;
    margin-bottom: 20px;
    letter-spacing: 1px;
    font-weight: bold;
}