HTML Tidy has a bug whereby it improperly indents comments; the more you run tidy, the worse it gets.
For example, if your code looks like this:
Code: Select all
<!--
This is a test
-->
Code: Select all
<!--
This is a test
-->
Code: Select all
<!--
This is a test
-->
This bug has been reported to the Tidy project. Unfortunately, it is an old bug and has a low priority.