Non broken lines are fine in Safari.

<div>ABCDEFGHI</div>

`getBoundingClientRect()` returns the wrong height in Safari when there are breaks.

<div>ABC<br>DEF<br>GHI</div>

Wrapping the Range's startContainer in a span is a workaround for the issue.

<div><span>ABC</span><br>DEF<br>GHI</div>