main {
    max-width: 22em;
}

#display {
    width: 100%;
    height: 1.2em;
    padding-top: .4em;
    font-family: monospace;
    font-size: 2.5em;
    text-align: center;
    color: var(--bgRed);
    border: 1px solid #666;
    border-radius: .2em;
}

#keyboard {
    font-family: monospace;
    font-size: 2.5em;
    display: grid;
    grid-template-columns: repeat(4, 1fr);
    grid-auto-rows: 1.8em;
    gap: .3em;
}

#keyboard button {
    color: var(--text4);
    width: 2em;
    height: 1.8em;
    border-radius: 0.5em;
}

#clear {
    background: var(--bgRed);
}

.number {
    background: var(--bgGreen);
}

#delete {
    background: var(--bgRed);
}

.operation {
    background: var(--bg4);
}