Pages are perfect by default (except for a serif font being by default on some screens and the line length not being limited to something readable).
The less you do, the best the web page behaves.
The more you fight against default behaviors / layouts, the more things break.
But more specifically, be careful with margins, they grow with the zoom level, often more than wanted. Same for position. And be careful with sizes fixed using something else than percentages for the same reasons. If you don't want a block be larger than 100ish characters for readability, use max-width with a font related unit, not straight width and not some other kind of unit.
The less you do, the best the web page behaves.
The more you fight against default behaviors / layouts, the more things break.
But more specifically, be careful with margins, they grow with the zoom level, often more than wanted. Same for position. And be careful with sizes fixed using something else than percentages for the same reasons. If you don't want a block be larger than 100ish characters for readability, use max-width with a font related unit, not straight width and not some other kind of unit.