body {
    display: flex;
    justify-content: center;
    align-items: center;
    height: 100vh;
    margin: 0;
    background-color: #000;
    font-family: Arial, sans-serif;
}

.calculator {
    background-color: #000;
    border-radius: 20px;
    overflow: hidden;
    width: 100%;
    max-width: 400px;
}

.display {
    background-color: #000;
    color: #fff;
    font-size: 36px;
    text-align: right;
    padding: 20px;
    min-height: 60px;
}

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

button {
    border: none;
    font-size: 12px;
    padding: 10px 5px;
    cursor: pointer;
    height: 40px;
    display: flex;
    justify-content: center;
    align-items: center;
}

.number {
    background-color: #333;
    color: #fff;
}

.operator {
    background-color: #f1a33c;
    color: #fff;
}

.func {
    background-color: #a5a5a5;
    color: #000;
}

.zero {
    grid-column: span 2;
}

button:active {
    opacity: 0.7;
}