When reviewing a pull request I find it hard to see the changes made since my last set of comments and to find unanswered comments (especially when the comment

When reviewing a pull request I find it hard to see the changes made since my last set of comments and to find unanswered comments (especially when the comment was on a diff hunk that is now gone). When responding to a review I find it likewise hard to find comments that I haven't responded to yet. Rietveld or gerrit solves all of these issues very easily. Do you have any tips on how to deal with them in github/bitbucket pull request UI?