trouble with inline html

I am having trouble with inline html tags in my README.md file.

From what I have read about Daring Fireball's Markdown, Redcarpet and Upskirt, a simple span element should suffice for adding styles, like this.

```
<span style="color:#F00;background-color:#555">TODO</span>: Fix inline-html in README.md
```

However, these tags are removed from html output.  What am I missing?

Thanks, -S.
