Should css class names like 'floatleft' that directly describe the attached style be avoided?

Question

Lots of websites use class names like floatleft, clearfloat, alignright, small, center etc that describe the

Answer 1

The main problem with having classes named floatleft, clear or the like is the fact that changes in the design imply changes in the HTML markup. This should not happen, true separation between content and presentation is achieved only when you can re-use the same markup in multiple designs or even media (think sharing the same HTML between desktop and mobile versions of your site and only switching sylesheets).

Now, for a practical example :). To add on Fredrik's answer, LESSCSS allow you to hide styles declarations/mixins from developers. This way you can protect reusable components in your stylesheets without the danger of having them pop up in your HTML.

Sample markup:

Company Name

Sample less code:

// example of reusable functions
.noText() {
    color: transparent;
    text-indent: -9999px;
}
.clear-after() {
    &:after {
        content: ".";
        display: block;
        visibility: hidden;
        height: 0;
        clear: both;
    }
}

.branding {
    .clear-after();
    .noText();
    background-image: ...;
}

Of course, for mobile you might just want to have the company name in bold, without any other styling:

.branding {
    color: pink;
    font-weight: bold;
}