* {
    margin: 0;
    padding: 0;
    box-sizing: border-box;
}

main {
    width: 220px;
    text-align: center;
    margin: 2rem auto 0;
    background-color: black;
    padding: 2rem 1rem;
    border-radius: 1rem;
}

button {
    width: 2.25rem;
    height: 2.25rem;
    margin: .25rem .1rem;
    border-radius: 50%;
    border: none;
    font-size: 1.25rem;
    font-weight: 600;
}

button:hover {
    cursor: pointer;
    background-color: lightgray;
}

.display {
    background-color: whitesmoke;
    height: 3rem;
    max-width: 180px;
    margin: 0 auto .5rem;
    padding: .25rem;
    border: none;
    text-align: right;
    font-size: 1.25rem;
}

.clear-btn {
    margin-right: .7rem;
    border-radius: .25rem;
    height: 1.25rem;
    width: 4.85rem;
    font-size: 1rem;
    font-weight: 600;
    background-color: orange;
}

.clear-btn:hover {
    background-color: darkorange;
}

.row:last-child {
    text-align: right;
}