These conflict with lightbox-viewer. I believe they need to be lower than lightbox-viewer's z-index in case the sidebar opens something like an image in the lightbox-viewer. Please see and update Z_INDEX.md as well.

@aghassemi - sidebar should have the highest zindex on the page. when we open a lbv from a sidebar we need to make sure it closes. isn't the z-index file autogenerated?

@camelburrito created #6712. Z_INDEX.md is not auto-generated AFAIK.

@aghassemi i think @erwinmombay has a script that generates it

Not fixed: see https://www.google.com/amp/cdn.relaymedia.com/amp/www.civilbeat.org/2016/12/ige-hawaiis-food-sustainability-a-priority-in-his-budget-plan/#amph=1 and https://www.google.com/amp/amp.gospelherald.com/articles/68178/20161122/christian-forces-retake-ancient-monastery-from-isis-vow-to-rebuild-we-are-stronger-than-they-imaged.htm#amph=1 for examples of how the sidebar is obscured by the fixed header when in a viewer. We really need to get the !important removed from the sidebar z-index so we can make this choice ourselves.