body{
    margin: 0.5em;
    background-color: red;
}

#speed {
    position: relative;
    font-size: 8em;
    font-family: Arial;
    background-color: rgb(78, 101, 50);
    color:lightsteelblue;
    padding-right: 0.2em;
    border-radius: 100px;
    text-align: end;
}

#speed::before{
        content: 'm/s';
        color: aliceblue;
        text-align: left;
        position: absolute;
        left: 2em;
        top:50%;
        font-size: 0.18em;
        translate:0% -50%;
    }