 Unsupported style property margin-top. Did you mean marginTop?

Hi, I am just testing out your module and I have the following in my console:

```
Warning: Unsupported style property margin-top. Did you mean marginTop?
    in div (created by Header)
    in a (created by Header)
    in div (created by Header)
    in Header (created by Tweet)
    in div (created by Tweet)
    in div (created by Tweet)
    in Tweet (at TwitterPreviewField.js:22)
```