I propose to consider the possibility of creating a fake widget, which is needed only in preview mode, but does not participate in the code on the storefront. Such a block is needed for the normal display of templates (Section) and content of individual pages. Example. If there is such a block, then I can give it indents and a background for easy editing. Or any other solution that makes it easier to edit pages that are missing indents or have an inconvenient background.
without fake block
with fake block
NOW
At the moment I’m using my own style
.brx-body.iframe.mounted {
padding: 100px;
}