Problem/Motivation
I guess the grey thick borders were supposed to be shown only while editing the text with CKEditor, but by default (with Drupal 10.3.6 and both Olivero & Claro themes) they are styled anywhere there is a section html element, for example on the node being viewed (even without having manually inserted them) if there is also a form with CKEditor on the same page (by default any node with comments enabled).
Proposed resolution
Change the section and section:before declarations to .ck-editor__editable section and .ck-editor__editable section:before to make the CSS apply only to sections within the CKEditor text area.
Issue fork ckeditor_section-3482277
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Comments
Comment #2
kopeboyComment #5
sadysierralta commentedComment #7
timohuismanThanks for your contribution!
Comment #8
timohuisman