Formatting each part/section/subsection

Question

Are there some magic lines to be placed in the preamble that would, like in CSS, specify how each generic section or subsection in the whole document should be formatted?

Answer 1

You can use the titlesec package for this.

A short example would be \titleformat*{\section}{\itshape} to change the style of \section to \itshape. See the package manual for more details.

See also:

What's the right way to change display of chapter headings?

How to format the chapter heading?

Formatting a \paragraph to look like a \section

or questions tagged with titlesec.

Answer 2

there are a lot of packages which support customizing titles and headers:

http://mirror.ctan.org/help/Catalogue/bytopic.html#title