As a web designer I've designed more projects in Photoshop. I've worked so many details which you are looking for.
In my projects background does not interrupt the text, text is big enough to read, but not too big, the hierarchy of information is perfectly clear, columns of text are narrower than in a book to make reading easier on the screen, navigation buttons and bars are easy to understand and use, Navigation buttons and bars provide the visitor with a clue as to where they are, what page of the site they are currently on, a large site has an index or site map, link colors coordinate with page colors, buttons are not big and dorky, every graphic link has a matching text link, graphics and backgrounds use browser-safe colors, good use of graphic elements (photos, subheads, pull quotes) to break up large areas of text, every web page in the site looks like it belongs to the same site; there are repetitive elements that carry throughout the pages, each layers are in the groups and renamed, flat and modern designs.