My biggest gripe with HTML is that line breaks add a tiny bit of space between elements. (jsFiddle.)
This can screw up layouts where child elements are sized to exactly fit their parents.
I read somewhere that you can remove this implicit padding - while still keeping the code somewhat legible - by using comments like this:
<!--
--><div>Foo</div><!--
--><div>Bar</div><!--
--><div>And so on...</div><!--
-->
This works, but I feel like there has to be a better solution. What other ways are there to work around the line-break padding?