Adjust availability of #header itself
Adjust #header before transition
Adjust #header appearance according to its status
Adjust appearance of buttons in disabled #header
Show #configure over #header
Merge branch 'disable-header-while-configuring'

Close gh-91.
Refine the order of notification_table
Refine the order of #notification CSS
Add comments on ambiguous events
Change the icon for "new version is available"
Update #tips on offline mode notifications
Merge branch 'refine-offline-mode-notifications'

Close gh-96.