I know this is old, but I'm bumping it because it helped me out. Also,
one other tip for collection_select:
If you don't need the prompt, you can use this:
…, {}, { "style" => "width:200px" }
But note that none of these are good ideas. Style attributes do not
belong in good HTML. Instead, use a separate CSS file. (For best
results, add Sass and Compass into the mix.)