Shaking tab in pipeline view

Summary

In this MR !8401 (closed) when I click to expand the failed test from https://gitlab.com/gitlab-org/gitlab-ce/pipelines/5627432 pipeline in pipeline tab and hover on dropdown. It start shaking as shown in gif

Steps to reproduce

1. Go to pipeline tab in !8401 (closed)
2. Click the failed test icon of https://gitlab.com/gitlab-org/gitlab-ce/pipelines/5627432 pipeline to expand the dropdown
3. Hover between failed and passed test in that dropdown

Expected behavior

this should not shake the screen

Actual behavior

It should not shake when user hover

Possible fixes

It can be a padding issue or may be arises from system font

/cc @filipa @iamphill