I’ve finally figured it out.
Whipped up a user script to correct this horrible design flaw that came out with yesterday’s update.
Script and instructions are up on my site: https://wuffleton.com/code/tumblrsidebar/
I’m not responsible if this script burns down your house or starts a nuclear war, but it should at least work with Chrome and Firefox (possibly others, but untested)! Hope this is of use to some of you :3
Updated with a few minor fixes for Xkit users! Should not interfere with the button and shouldn’t go below Xkit sidebar elements (hopefully)!
This is the guy who helped me with my sidebar. Go support him and shit.