When To Use And Not to Use a Class

When to Use a Class
As described previously, classes are a very flexible method for applying your CSS rules, and can
be used again and again within a page. Use classes to control elements that belong to a group,
for temporary items, and also to enhance the behavior of an ID.

When Not to Use a Class
It is not recommended that classes be used for main structural elements within a page, such as
headers and main navigation, although they will work. Doing so would decrease the flexibility
of your design and make further customization difficult without overhaul or extra markup.
Also, be sure a class is needed, and make sure the element cannot be targeted by defining a rule
for the existing (X)HTML before getting class-happy. Remember that a class is used for exceptions
to normal styling, and not to define the standard.