header with nav bar (as one background-image) could be possible but content changes in height in following website pages; which still gives the gap problem. As I wrote: i tried many options but non so far was of help. Hope to find on this forum the css hero! Even position: top etc. doesn’t work. Cover dus not work, etc.
^This.
A site design is built around actual content, not block of imaginary space defined by imaginary numbers.
Add actual content and the process may begin.
The key to RWD is that an elements size is defined by its content, not “magic numbers”.
Without content, you don’t have a page, there is nothing to style, why bother?
You are hanging wallpaper on a wall that has yet to be built.
The gap isn’t a hard problem to solve. Understanding the content flow is more difficult when the background images are part of an overall pattern. You mention that the content changes on different pages but how does that bottom image segment change? Does it stretch and compress or repeat (unlikely) or how do you want it to behave?
Then I assume there is to be a menubar near the top. How does that background image behave at narrowing widths or if the user chooses a larger font size than you use?
The puzzle is not the gaps as much as it is understanding how the images are to behave with different and viewports. The images are bound to distort.