@jonatandor35 creating a custom element does not work for what I need, since custom elements are just “custom boxes”, but they still are considered as Wix elements outside their boxes, I can only code stuff inside a custom element’s box, not its own properties in Wix editor.
For what I want to do, I need to make something like this:
$w("#strip").offsetHeight = window.innerHeight;
But offsetHeight and window.innerHeight aren’t defined in Wix editor.