Field Label Color and Description Visibility for Deep (4th/5th Level) AJAX Media Library Forms

Problem/Motivation

When opening nested AJAX UI forms that reach the 4th or 5th level inside the Media Library modal
(e.g., Add Media → Entity Browser → Media Edit Form), the following UI issues occur:

• Field labels lose their correct color
  - Labels appear too light or inherit wrong opacity, making them unreadable.
• Field descriptions become difficult to read
  - Description text blends with the modal background.
• Required field asterisks are barely visible
  - Especially inside deep AJAX-loaded forms.
• Media Library form wrapper styling is inconsistent
  - Borders, padding, and background layers overlap incorrectly.

These issues only appear in deep AJAX form nesting, not on first-level forms.
Screenshots confirm that the problem is triggered when the form is loaded multiple times inside layered modals.

Steps to reproduce

1. Open a page with Layout Builder or any modal-based editor.
2. Add a block requiring an image.
3. Click Add or Select Media → triggers AJAX modal.
4. Upload an image → triggers another inner AJAX form.
5. Observe the 4th/5th level media edit form.
6. Notice:
- Label color incorrect
- Description text unclear
- Required asterisk nearly invisible
- Form wrapper border mismatching

Actual Result

• Label text is low-contrast and difficult to read.
• Descriptions barely visible.
• Required field markers lose color styling.
• Modal form does not inherit Varbase form styling in deep nested AJAX calls.

Proposed resolution

• Limit for drupal-off-canvas and layout-builder-modal
• Not to apply to all UI Dialog

Remaining tasks

• ✅ File an issue about this project
• ✅ Addition/Change/Update/Fix to this project
• ✅ Testing to ensure no regression
• ➖ Automated unit/functional testing coverage
• ➖ Developer Documentation support on feature change/addition
• ➖ User Guide Documentation support on feature change/addition
• ➖ UX/UI designer responsibilities
• ➖ Accessibility and Readability
• ✅ Code review from 1 Varbase core team member
• ✅ Full testing and approval
• ✅ Credit contributors
• ✅ Review with the product owner
• ✅ Update Release Notes and Update Helper on new feature change/addition
• ✅ Release varbase-10.1.0, varbase_layout_builder-10.2.0-rc1, varbase_layout_builder-10.2.0-rc2, varbase-10.0.9, varbase_layout_builder-10.1.17, varbase_layout_builder-10.1.18

Varbase update type

• ✅ No Update
• ➖ Optional Update
• ➖ Forced Update
• ➖ Forced Update if Unchanged

User interface changes

After the fix:

API changes

• N/A

Data model changes

• N/A

Release notes snippet

• fix: #3561009 Field Label Color and Description Visibility for Deep (4th/5th Level) AJAX Media Library Forms