Since around the introduction of the new HTML and Rich Text Editor for Pages, the layout of one of our courses has ben crippled. We spotted the issues on 8th September this year, although they may have occurred earler as the course was inactive at the time. We were using an alternative menu structure to overlay the left hand menu (Home, Modules, etc.) and the top breadcrumb trail. This worked exactly as we had hoped until a change in the page layout ocurred. During page load the menu appears in the correct position but is then moved as the page loads further.
I have been back and forth with Instruture Support for the past 7 weeks. All they have tried is to point fingers at me but then disengage when their assertions are shown to be incorrect (at one point accusing me of pirating their code through the Consol). Then they return to their fall back position, saying they don't support custom HTML or CSS. They told me that "we began enforcement of the banned html tags" (but then refused to identify those tags in my code, just directing me to the list of allowed HTML) and one of them let slip that they "are stopping any interface elements being overlayed" but then said no more when asked to expand on the statement. They also say that nothing has happened on the platform that they are aware of that could cause this issue (make your minds up please). None of this gives me faith in their technical ability, nor in their desire to support users. Their claim to be "working hard to meet the needs of all Canvas users" is clearly not true in this case.
The clearest change that we are seeing is that the 0,0 position on the page is being changed during load and that our menu elements that previously could overlay Canvas elements are now forced behind them. Any help in resolving this issue would be gratefully received.
My sincerest apologies that you feel as though you are getting mixed messages.🙁
I don't have an answer to your more technical questions, but I can provide our position on supporting custom work. I am pretty confident you are familiar with this, but wanted to make sure. You can find it in the highlighted box at the top of this guide.
To help with the technical questions in the thread here it may be good to move this discussion to the Developers Group where other users with skills and talents like yours are solving similar things? Let me know if you'd like me to do that.