fix(layout): allow flex-offset to be a child of layout-margin

[bersLucas]

Adds .layout-margin to the layout-offset selector for more specificity

Fixes #11328

PR Checklist

Please check that your PR fulfills the following requirements:

• The commit message follows our guidelines
• Tests for the changes have been added or this is not a bug fix / enhancement
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PR Type

What kind of change does this PR introduce?

[x] Bugfix
[ ] Enhancement
[ ] Documentation content changes
[ ] Code style update (formatting, local variables)
[ ] Refactoring (no functional changes, no api changes)
[ ] Build related changes
[ ] CI related changes
[ ] Infrastructure changes
[ ] Other... Please describe:

What is the current behavior?

The CSS class .layout-margin overwrites the margin-left declaration from .flex-offset-*, so it doesn't get offset to the right.

Issue Number: #11328

What is the new behavior?

.flex-offset now includes .layout-margin in it's CSS selector to increase specificity and not have it's margin overwritten by .layout-margin when it is a child of .layout-margin

Does this PR introduce a breaking change?

[ ] Yes
[x] No

Other information

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[bersLucas]

I signed it!

[googlebot]

CLAs look good, thanks!

[Splaktar]

Thank you for your contribution! It looks good other than the one space issue that I mentioned.

[Splaktar]

It looks like the extra space at the start of the line breaks the alignment of the code here? Can you please remove that one space?

[bersLucas]

Fixed in 6e4b733

[Splaktar]

LGTM