Support css={...} syntax?

[FezVrasta]

Hi, thanks for the theme, it looks great!

I was wondering if you could add support for the css property syntax?

<div css={`
  color: red;
`} />

Right now the template literal is all green rather than highlighted as if it was css. I need to explicitly use the css tagged function to make the syntax work:

<div css={css`
  color: red;
`} />

Considering it's a feature supported by Styled Components and Emotion I think it would be useful to a lot of people.