changing <h6> tags to <h2> tags

I’m using the F8 Lite theme, and all of the homepage and category post titles are (for some reason) in <h6> tags by default. Naturally I want to change this to <h2> tags.

I found the code making it happen in style.css under “Archive”

h6.archive-header {display:block;border-bottom:#000 1px solid;margin:0 0 .5em;}

Which is triggered like this around the site:

<h6 class=”archive-header”>POST TITLE</h6>

So I tried to make a new style and write it in style.css, using the exact same formatting as the h6 class, like this:

h2.post-link {display:block;border-bottom:#000 1px solid;margin:0 0 .5em;}

I then went into home.php, and changed h6 class=”archive-header” to h2 class=”post-link”>, and made sure to close the tag correctly with </h2>. When I saved and went to the homepage, it didn’t work. The post links aren’t bolded, and the spacing is wrong as well. Why didn’t this work?

Any ideas?