span {
    color: white;
    background-color: #343132;
    Box-shadow: 0.5em 0 0 #343132,-0.5em 0 0 #343132;
}

div {
    width: 100px;
}

<div>
    <span>Do you have an idea to add a background-color property on a multi-line text,with two difficulties:</span>
</div>