Custom CSS for SOME Links

Taellosse

So I'm experimenting with custom CSS to install in one of my ongoing campaign sites. I should stress that I'm not very experienced with CSS. I have a working knowledge of basic HTML, and I've become reasonably conversant in textile from using it on OP, but CSS is pretty new to me. At present I'm fiddling on a test campaign, so as not to impact the usability of the real one. I've got things more or less how I want, but I'm stuck on this one thing.

I've defined (I think), in the global CSS, alternate link behavior, which I want to use in table headers and the like. It reads as follows:

.header-content a:link {color:lightblue;text-decoration:underline;}
.header-content a:visited {color:lightblue;text-decoration:underline;}
.header-content a:hover {color:skyblue;text-decoration:none;}
.header-content a:active {color:royalblue;text-decoration:underline;}

And I've tried to apply it to the main wiki page, which I have set up as a div-table. When I add ..., wrapped around the ... that defines the two sections whose headers are also links, it appears to work properly in the preview, but when I save the changes, the final version of the page ignores it, and the link behavior remains the standard defined for the whole site. Is there something I'm doing wrong, or is this just not actually possible to do with the limited global CSS that has been implemented on OP?