[css-flexbox] Broken example formatting, #main is floated right

I noticed a formatting/styling issue.  In a few examples in the latest spec
(http://www.w3.org/TR/2015/WD-css-flexbox-1-20150514/), there are `#main`
selectors that appear on the right edge of the document.  In the previous
draft (http://www.w3.org/TR/2014/WD-css-flexbox-1-20140925/), the examples
weren't styled, and `#main` appeared in-line with the rest of the example.

I assume this was an oversight.  The floating is confusing, especially the
`#main#main#main` appearing to the right of `> article,  > nav,  > aside {`.

The `#main` selector is a span element of class `token id`:

    <span class="token selector"><span class="token id">#main</span> </span>

`span.id` is assigned `float: right` by `default-TR.css:15`:

  span.id {float: right; font-weight: bold}

-Ryan