XML comments viewed in browser

[Ha]

I have the following piece of XML:
<?xml version="1.0" encoding="UTF-8" ?>
<TopLevel> <!-- TopLevel comment -->
<SubLevel /> <!-- SubLevel comment -->
</TopLevel>

When viewed in the browser it looks like this:

<?xml version="1.0" encoding="UTF-8" ?>
<TopLevel>
<!-- TopLevel comment -->
<SubLevel />
<!-- SubLevel comment -->
</TopLevel>

This makes it hard to determine which element the comment refers to.
Is there a way to have the comments output on the same line, or is
this dependent on the browser?

Finally, should comments generally be placed before the element is
defined?

Thanks.