Annotate button does not account for margins of offset parent

[AndyAyrey]

Using 1.2.7; experience the bug as described here: hypothesis/h#371

With a structure like this:

<section style="margin-top: 200px;"> 
  <div class="content>
     <!-- content, wrapped in annotator div --> 
  </div>
</section>

The annotate button will appear offset vertically by 200px. Perhaps related to af0658a and to #243?

[nickstenning]

🍰

[AndyAyrey]

You guys are amazing. Thanks for all your hard work!