Fix bext options page > advanced settings

Created by: erzhtor

Closes https://github.com/sourcegraph/sourcegraph/issues/30897.

Description

After https://github.com/sourcegraph/sourcegraph/pull/30621 browser extension > advanced settings button/link styles were broken.

Screenshots (TODO: if applicable)

Before	After

Before merging

• Test on different code hosts (if applicable)

  • GitHub
  • Gitlab
  • GitHub Enterprise
  • Refined GitHub
  • Phabricator
  • Phabricator integration
  • Bitbucket
  • Bitbucket integration

• Test on different browsers (if applicable)

  • Chrome
  • Firefox
  • Safari

• Add change log message to client/browser/CHANGELOG.md, under "Unreleased" section. (if applicable)

Test plan