href inside of span floated right not clickable

Version 0.7.1

A href tag inside of a span is not clickable in MacDown. When saved to github or mkdocs it works as it should. Click on the link and go to the tag at the top of the file.

When tried with a DIV the formatting goes completely crazy.

```
Back to Top
```

using markdown inside of span behaves similar.

```
[Back to Top](#top)
```

Reproduce the issue in MacDown 0.7.1 using the provided span, float, and anchor examples, then compare the rendered link with GitHub or MkDocs. Trace the Markdown-to-HTML rendering entry point and verify that the anchor is clickable while the floated layout remains intact.

Written by the indexing model from the issue text.