html {
    height: 100%;
}
body {
    display: flex;
    justify-content: center;
    align-items: center;
    height: 100%;
}

#test {
    display: inline-block;
    font-size: 20pt;
    font-family: SF Mono, Consolas, mono, sans-serif;
}

#cursor {
    border-left: 3px solid black;
    height: 1em;
}

@media (prefers-color-scheme: dark) {
    html {
        background: #333;
        color: #FFF;
    }

    #cursor {
        border-left-color: #FFF;
    }
}