Thanks for the reply! Yes, there JS controls everything. Your example works on codepen but not in my case)
The problem is that js controls the adaptability while maintaining the exact proportions of the background image, or rather scene (background image with animation icons is one common scene) ie you can only select one, stretch the stage to the width of the viewport or the height of the viewport.
Let's choose width ( live example here honey31.esy.es
) - then at the height of the image does not fit in 100vh on a widescreen monitor and the bottom edge goes into scrolling.
If you choose "scale by height" - the image is 100vh, as if everything is great, but the edges on wide angle white streaks appear, i.e. no scales to width 100%.
In General, the main problem is that the scene (bg + animated icons) always maintains the proportions 1200х720.
In the question I meant how to make it so that the stage could be run as a normal background? If background'have to set the cover - the picture always fits in any format, a square screen, wide angle, when the "background-size: cover" makes no difference.
Whether it is possible in my case to set the stage property to cover? To make the scene adjust to any screen format.
In my example the scene is set classes class="bg Stage_bg"
The task is a difficult hike, except you, no one dare to answer at all
In any case - Thank you)
By the way, a little writing on the website can be a living example and problems with the main screen be viewed here honey31.esy.es