Fix riverstoryscroll on narrow viewports

[rezrah]

Summary

Fixes RiverStoryScroll on narrow viewports.

Previously didn't render the layout correctly at all on various browsers, due to incorrect CSS nesting.

Fixed by cleaning up the CSS file

Tested working in Next.js in Chrome 👇

https://github.com/user-attachments/assets/00afcd3c-03d7-4be5-8579-22616d4d5e6d

List of notable changes:

• Fixed the layout bug
• Tweaked pagination position

What should reviewers focus on?

• Only way to verify the fix is outside of Storybook.
• Code review is sufficient at this point

Supporting resources (related issues, external links, etc):

• Original bug report in Slack

Contributor checklist:

• [ ] All new and existing CI checks pass
• [ ] Tests prove that the feature works and covers both happy and unhappy paths
• [ ] Any drop in coverage, breaking changes or regressions have been documented above
• [ ] New visual snapshots have been generated / updated for any UI changes
• [ ] All developer debugging and non-functional logging has been removed
• [ ] Related issues have been referenced in the PR description

Reviewer checklist:

• [ ] Check that pull request and proposed changes adhere to our contribution guidelines and code of conduct
• [ ] Check that tests prove the feature works and covers both happy and unhappy paths
• [ ] Check that there aren't other open Pull Requests for the same update/change

Screenshots:

Please try to provide before and after screenshots or videos

Before	After
	

[changeset-bot[bot]]

🦋 Changeset detected

Latest commit: 5c49d8b688bae2483367c1ce40a067c76ab4a16b

The changes in this PR will be included in the next version bump.

This PR includes changesets to release 6 packages

| Name | Type | | ------------------------ | ----- | | @primer/react-brand | Patch | | @primer/brand-primitives | Patch | | @primer/brand-e2e | Patch | | @primer/brand-fonts | Patch | | @primer/brand-config | Patch | | @primer/brand-storybook | Patch |

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[github-actions[bot]]

🟢 No design token changes found

[github-actions[bot]]

🟢 No visual differences found

Our visual comparison tests did not find any differences in the UI.