The direct answer to the question is right below this one, by Curt.

If you're interested in CSS class naming conventions I suggest to consider one very useful convention named BEM (Block, Element, Modifier).

UPDATE

Please read more about it here - http://getbem.com/naming/ - that's a newer version that renders the following answer obsolete.

---

Main principles:

• A page is constructed from independent Blocks. Block is an HTML element which class name has a "b-" prefix, such as "b-page" or "b-login-block" or "b-controls".

• All CSS selectors are based on blocks. There shouldn't be any selectors that aren't started with "b-".

Good:

.b-controls .super-control { ... }

Bad:

.super-control { ... }

• If you need another block (on the another page maybe) that is similar to block you already have, you should add a modifier to your block instead of creating a new one.

Example:

<div class="b-controls">
    <div class="super-control"></div>
    <div class="really-awesome-control"></div>
</div>

With modifier:

<div class="b-controls mega"> <!-- this is the modifier -->
    <div class="super-control"></div>
    <div class="really-awesome-control"></div>
</div>

Then you can specify any modifications in CSS:

.b-controls { font: 14px Tahoma; }
.b-controls .super-control { width: 100px; }

/* Modified block */
.b-controls.mega { font: 20px Supermegafont; }
.b-controls.mega .super-control { width: 300px; }

If you have any questions I'd be pleased to discuss it with you. I've been using BEM for two years and I claim that this is the best convention I've ever met.