Feedback dialog text escapes dialog

[jsoref]

Steps

1. Visit https://cs.github.com/?scopeName=All+repos&scope=&q=something#
2. Click Give feedback at the top right
   
3. Click the expander at the bottom right of the text box and drag it downward
   

Expected results

1. The bottom of the box shouldn't escape the dialog
2. It'd be really nice to be able to make the dialog wider -- it's really narrow. Compare with this page: