Functional CSS

Functional CSS (sometimes called atomic CSS) is a strategy where we have a largely static set of small, single-purpose, highly-presentational classes that we combine to achieve a certain look. For example, there might be a class named fwb that does nothing but set font-weight to bold, and another called ttu, which sets text-transform to uppercase. To style some content in bold uppercase, we’d use class="ttu fwb".