Add small variant to underline nav

[pksjce]

Describe your changes here.

Changed font-size and padding values to add a small variant.

Screen.Recording.2022-08-11.at.4.41.23.pm.mov

Closes https://github.com/github/primer/issues/982

Merge checklist

• Added/updated tests (added storybook arg)
• Added/updated documentation
• Tested in Chrome
• Tested in Firefox
• Tested in Safari
• Tested in Edge

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[changeset-bot]

🦋 Changeset detected

Latest commit: cf0f980

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

This PR includes changesets to release 1 package

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@primer/react	Patch

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[github-actions]

size-limit report 📦

Path	Size
dist/browser.esm.js	75.63 KB (0%)
dist/browser.umd.js	76.24 KB (0%)

[mperrotti]

We should vertically center the icons in their container using something like this:

display: inline-flex;
align-items: center;

They look a little "off" now when variant === 'small' :

Everything else looks good though! 👍

[mperrotti]

@pksjce - I pushed a commit to adjust the vertical alignment of the icons. If you don't feel like we need to pair later, you can remove the meeting from the calendar.

[pksjce]

Thanks! @mperrotti . I was trying the same at the linkStyles 🤦‍♀️ Will go ahead and merge this!