Cascade A single style sheet associated with one or more web pages is valuable, but in quite a limited way. For small sites, the single style sheet is sufficient, but for larger sites, especially sites managed by more than one person Pseudo-classes Pseudo-classes are classes that define style rules for certain tag states. Pseudo-classes must be associated with their tags and are separated from them by a colon instead of a period. The pseudo-classes also use predefined key words, as opposed to other classes, which you name yourself.