[Tex2002ans]

Originally Posted by Doitsu

I only had to add height:100vh; to the cover svg code of the epub3 book for ADE4.

Ahh, I did not test EPUB3.

Want to attach a sample EPUB3 so we could more easily test these different readers/variants?

Side Note: Still sounds like something ADOBE should be fixing in their reader...

Originally Posted by Turtle91

I had issues with full screen images ‘bleeding’ into a 2nd page when I used 100%. [...]

Yes, I've seen this too, especially in the browser-based or mobile Android apps (like PocketBook Reader).

Jellby has described the technical details many times over the years, where users expect height="100%" to:

• match the height of the screen

... but that's not correct. It's:

• the height of the parent container.

Everyone agrees on 100% width, and it works as expected, but 100% height leads to all sorts of oddities/conflicts across implementations.

Then you have to take into account headers/footers (from reader/app/OS)—so again, the 100% "screen height" you expect isn't actually taking up the entire screen.

This is why:

• CSS3's vh + vw units were created.
  
  • vh + vw = VIEWPORT width/heights!
    
  • % = CONTAINER width/heights!
    

AND THEN, the crux of this "blank page" problem, is an internal rounding issue. Imagine, after the headers, footers, OS/reader info, you had:

• 1110px height available

... but then it "100% scaled" the height of the image to:

• 1110.1px

This is why:

• The "98% hack" was sometimes suggested as well.
  
  • 98% would ensure scaled height would always fall below, even if there was a slight "rounding-up" error.
    

The issue with new CSS3 units—like vh/vw + rem—is that they wouldn't work on older devices/readers.

The SVG wrapper is/was the ultimate solution to all of these though. :P

- - -

Side Note: For more info on vh/vw, also see:

• CSS-Tricks.com: "Fun with Viewport Units"

For more info on the "98% hack" + "blank screen after images", see previous discussion in:

• 2022: "Remove blank pages"

I was never a big fan, so I never promoted the "98% hack"... but I wouldn't fault others for trying to squash the "2nd blank page" issue if they were SO annoyed by it.

Side Note #2: This a bug/issue in some small minority of readers, so I would strongly vote against changing Sigil's correct 100% (or 100vh) Add Cover into 98% just to appease this quirk.

ADE needs to fix their crap!

And if you, as an ebook creator/reader, are annoyed by that 2nd blank page (on whatever device you're using), then you can do that manual code adjustment afterwards.

That's just my 2 cents!