If code implementation is off topic in this community, then what would be suitable question regarding HTML or CSS? because the tags exist...
What are HTML and CSS tags all about?
2 Answers
If you look at the highest voted CSS questions, the top 6 have little or no code at all. The HTML tag is similar. So there is obviously scope for non-implementation questions. But that isn't to say implementation questions are off-topic per-se.
The tag info for CSS says (emphasis mine):
Questions about cascading style sheets, commonly refered to as CSS. Ask anything related to implementing styles, effects or graphic-design-specific tasks. For questions about implementing structural elements or anything completely unrelated to the aesthetic look, please go to Stack Overflow.
Some questions will be clear-cut, some not so much. Your question, which I voted to close, was about using a <div> to create a background effect (which is about the aesthetics) and your problem was that <div> affecting the position and structure of the rest of your page (which certainly isn't). More importantly, your question was a very basic CSS question which should have been easily answerable with a Google search or basic CSS positioning tutorials.
What are HTML and CSS tags all about?
Questions around designing in the browser with HTML and CSS.
HTML and CSS isn't off topic but I believe the issue you're referring to with your question, "How to prevent object's position being affected by other elements" is you do not show what you've tried or include any code.
