The following two lines should be visible without the white background clipping any of the text:

<p>
<span style="background-color: white; font-size: 20px;">
<span style="font-size: small; ">FOOBARBAZ<br>BAZBARFOO</span></span>
</p>

The background below should be 10x10 and snugly fit the image:

<p>
<span style="background-color: red; font-size: 40px;"><img style="width: 10px; height: 10px;"></span>
</p>