When citiing an entire website and not citing specific content, such as a particular document, it is sufficient to cite the url within the body of the paper only with no reference in the reference list.
The CSS Library website (http://libguides.css.edu/CSSLibrary) provides services and resources for all faculty, staff, and students who are currently affiliated with the institution.
Place the url in close proximity to where it is being discussed. It can be placed in the middle of the sentence, or at the very least, at the end of the sentence. Place the url in parentheses, and remove the hyperlink.
For more information, see page 32 in APA Style Guide for Elctronic References, 6th ed.