<div>
<!--White-space -->
<span>Some text here<span>
</div>

div {
    background: red;
}

span {
    background: blue;
    color: #fff;
}

div {
    background: red;
    font: 0/0 a;/*make text invisible for parent container with white-spaces*/
}

span {
    background: blue;
    color: #fff;
    ont: 12px/normal Arial, sans-serif;/*set back font for child container*/
    display:inline-block;/*just for good render effect*/
}