Steps to reproduce: 1. Select plugins to update in plugin manager 2. Click "Download now and install after restart" button 3. Wait for plugins to say "downloaded successfully. will be activated during next boot" 4. Click the checkbox for "Restart Jenkins when installation is complete and no jobs are running" 5. Dark theme disappears while jenkins shows "Restarting jenkins" at the bottom of the plugin list 6. Dark theme reappears after jenkins has restarted.