I've used fancy header to create decorative lines at the top and
bottom of pages in a new book, but when I insert Sections first
thing on my new page (followed by a horizontal line) the white
space between the header and the section is bigger than the white
space between the section and the horizontal rule. Ideally, I would
like to decrease the upper white space, but redefining through
fancyhdr doesn't seem to be within my grasp.
**Example**
Header: ________________
Section: Section Title
H.Rule: ________________
The extra white space above Section is probably associated with the
Section environment. So you might try redefining the section
environment, or using a package like "titlesec" which makes it a bit
easier. A more crude hack might be to add a negative vertical space
above the section.