Four column layout sometimes unusable in Gin edit form in Chrome only

[ctorgalson]

This happens in Page Builder using a four-column layout from localgov_paragraphs_layout. As far as I can tell, it only affects Chrome-based browsers, but it's reliable any time any non-breaking content is larger than 1/4 the width of the edit form.

It also depends on how the content of each column is rendered in the form, so is not usually noticeable. But when all/several columns' content contain something like a long URL, the last 1-2 columns may become impossible to edit.

Reproducing the issue

1. edit a Subsite Overview page
2. using Page Builder, add a four-column section
3. in each column, create Link paragraph using something like https://github.com/localgovdrupal/localgov_paragraphs/issues/new for the URL
4. save the form
5. re-edit the page--it should resemble the above screenshot

Fixing the issue

Adding something like the following CSS to the layout's css fixes the problem neatly:

.gin--edit-form .layout--fourcol-25-25-25-25 > .layout__region {
    overflow: hidden;
}

If there's agreement that this is a good fix, I can make a PR. There aren't many other courses available to us, given the narrow size of the edit form with Gin's vertical tabs, but please suggest alternatives I haven't considered.