A: 

My first guess is that you're running into an issue with CSS specificity. There is a good article on it at http://www.smashingmagazine.com/2007/07/27/css-specificity-things-you-should-know/, so if you can include a container element ID, that may help.

Let me know if this doesn't turn out to be the problem and I'll come up with more ideas.

Eric Wendelin
No, I don't think that's right. For example: the `<div class="MapPopup">` should have a yellow background - that's not an issue of specificity.
Herb Caudill
I've never had a problem with styling, and the fact that only some styles are applied leads me to believe they are being overridden by other styles. As Zack suggested above, inspect the element with Firebug and see what's really affecting the font, etc.
Eric Wendelin
+2  A: 

As suggested I've gone in with Firebug to see what's going on. It looks like Google is doing two obnoxious things:

  1. It's stripping out all class attributes from my HTML.
  2. It's throwing all kinds of hard-coded styles around.

Here's my HTML along with the first couple of wrappers inserted by Google:

<div style="font-family: Arial,sans-serif; font-size: small;">
    <div id="iw_kml">
        <div>
            <h6>Concession</h6>
            <h4>BOIS KASSA 1108000 (Mobola-Mbondo)</h4>
            <p>
                Description goes here</p>
            <a target="_blank"><span />View details </a>
        </div>
    </div>
</div>

As you can see, my classes (e.g. MapPopup in my first div, Button etc. in the <a> tag) have all been stripped out.

Knowing this I'll be able to work around Google's interference, using !important and targeting the container div for the whole map - still, this is annoying, and unexpectedly clumsy coming from Google.

Herb Caudill
+2  A: 

More related obnoxiousness related to the HTML in a KML <description> block: Any links are given the attribute target="_blank", whether you like it or not. I'm currently exploring ways to undo that, using jQuery, but what a drag. I really don't understand why Google feels the need to tamper with this HTML.

See also this thread on the official Google Group.

Herb Caudill