Twenty Thirteen: Size of search box on no-results search results page seems small

[markjaquith]

Seems like this could be wider here. And maybe centered?

[Mamaduka]

We can make it full width like Twenty Eleven does.

[obenland]

I think 600px might be a little steep here. But how about 270px, like the comment form input fields?

[lancewillett]

What are the other places in the theme this wider width will change? 404, no results, toolbar search, widgets? Need to make sure the selector is specific enough just to style the search input in ".hentry" right?

[obenland]

Widget uses the old text input, navbar search is set to 230px when active.

[lancewillett]

In [23697] Twenty Thirteen: a bit wider search input in main content area. Props obenland, fixes #23765.

Also clean out one case of unneeded "px" value unit.