The broken lines are block regions. They are now labelled as such so that you know where they are on the page when editing. The 'empty' region 'discussion' has been mentioned: https://github.com/gjb2048/moodle-theme_essential/issues/751 - I've decided this afternoon that its a bug I need to deal with. Please be patient.
Themes
Essential theme and moodle 3.1.2
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