There are a few I’d like for more WordPress theme developers to consider standardizing across the board.

First of all, they are classes, so they shouldn’t semantically impact the content. This is important because if, in the future, some person shockingly decides to change themes, the content of their posts isn’t affected.

Image classes

First of these class would be image positioning classes: .alignleft, .alignright, and .center. Since the positioning and/or float of images should be determined by CSS in XHTML, I think these are probably the safest special classes to agree upon.

img.alignleft {
   float: left;
   margin: 0.5em 1em 0.5em 0;
}

img.alignright {
   float: right;
   margin: 0.5em 0 0.5em 1em;
}

img.center {
   display: block;
   margin: 0.5em auto;
   text-align: center;
}

I deleted the img element prefix from the descriptors above because I agree with Adam’s comment below. Still not sure about what to do about content columns.

An all-caps class

Another that I noticed first in Kubrick and have since seen all over the place is span.caps. I’m not sure why this came about, but I find it useful enough. It’s purely presentational.

span.caps {
   font-variant: small-caps;
}

This could also be text-transform:uppercase; with essentially the same use. A per theme choice, I suppose.

XFN relationship classes

I’m also adding XFN link classes to my theme revisions. Why? Because I’m fascinated with Microformats, frankly. I found these great microformat icons, notably the XFN relationship icons.

Now, there is a more technically accurate way to style links with XFN relationship attributes, as noted on the XFN intro page:

a[rel~="friend"]{
   background: url('xfn-friend.png') no-repeat center right;
   margin-right: 2px;
   padding: 2px 26px 2px 0;
}

But this, of course, requires the browser to be whooly CSS 2.1 compliant, i.e., handle CSS attribute selectors. And can we guess which browser doesn’t do this? (If you guessed IE, then you already knew the answer.)

Using attribute selectors in CSS can cause IE do all sorts of strange things, like ignore any inline selectors and following descriptors. Which means that not only will CSS not display an icon (as is set above) but might also screw up following CSS selectors. It’s touchy.

So this is my compromise. Which is fine, and forward-compatible:

a.xfn-friend {
   background: url('xfn-friend.png') no-repeat center right;
   margin-right: 2px;
   padding: 2px 26px 2px 0;
}

The downfall of this is that it would be undermined if the link had the class but not the rel="friend" attribute. Which would be deception by icon.

Anyhow, those are just the most minor of things I’ve been considering and I’d like to hear what others had to say on the subject.