CSS: Where is a tag being applied?

I'm working on a website for a volunteering organisation whose parent organisation ordered us to implement a rebranding and gave us several css sheets.

My problem 开发者_运维技巧is this:

A page is structured like so:

<h1>Heading</h1>
<p>blah</p>
<p>blah</p>
<p>blah</p>

From what Firebug tells me, the first paragraph is being given a p.intro property that is making it larger. What tool can I use to discover where the tag is being applied? There is nothing that specifies any css tags in the page.

Kind Thanks!

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Assuming that the HTML you are providing is what comes out of "View > Source" (so it isn't being mangled by any server side processing), then it is almost certainly coming from JavaScript.

Search through all the JS files for mention of "intro" and you'll probably track it down. If that fails, expand the search for the HTML files in case you have embedded JS.