<!DOCTYPE html>
<style>
    span { display:inline-block; width:1em; }
</style>
<p>Test removal of of a block between two spanners, then insertion of another block at the same position.</p>
<p>You should see three lines with the word "PASS" on a lime background below. Letter spacing is expected to vary.</p>
<div style="width:4em; background:lime;">
    PASS<br>
    <span>P</span><span>A</span><span>S</span><span>S</span><br>
    PASS<br>
</div>