body {
    background-color: #3a3939;
    display: flex;
    justify-content: center;
    align-items: center;
    height: 100vh;
    margin: 0;
    font-family: -apple-system, BlinkMacSystemFont, "Segoe UI", Roboto, sans-serif;
}

#calculator-root {
    background-color: #131313;
    width: 280px;
    padding: 15px;
    border-radius: 20px;
    box-shadow: 0 10px 30px rgba(0,0,0,0.3);
}

.display {
    color: rgb(166, 139, 167);
    font-size: 50px;
    text-align: right;
    padding: 20px 10px;
    min-height: 60px;
    word-wrap: break-word;
}

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

button {
    border: none;
    height: 60px;
    border-radius: 50%;
    font-size: 1.5rem;
    cursor: pointer;
    transition: filter 0.2s;
}

button:active {
    filter: brightness(1.5);
}

/* Colori dei pulsanti */
.btn-number { background-color: #71576a; color: white; }
.btn-operator { background-color: #95a6ad; color: white; font-size: 1.8rem; }
.btn-special { background-color: #c4c49a; color: black; font-size: 1.2rem; }

/* Il tasto zero è più largo */
.btn-zero {
    grid-column: span 2;
    border-radius: 30px;
    text-align: left;
    padding-left: 25px;
}