Thus, if there are conflicts between the style sheets of an incoming document and the reader's personal sheets, the author's rules will be used. Both reader and author rules override the UA's default style sheet. Imported style sheets also cascade and their weight depends on their import order. Rules specified in a given style sheet override rules imported from other style sheets. Imported style sheets can themselves import and override other style sheets, recursively, and the same precedence rules apply.
Declarations apply if the associated selector matches the element in question.
If no declarations apply, terminate the algorithm. An imported style sheet has the same origin as the style sheet that imported it. Rules in imported style sheets are considered to be before any rules in the style sheet itself. It is therefore important that the User Agent gives the user the ability to turn off the influence of a certain style sheet, e.g., through a pull-down menu. CSS attempts to create a balance of power between author and user style sheets.