Better vertical align for SAX title
Uncommented Number of Neighbors field and styled number type inputs
More generic .controls and .buttons CSS classes
Let's use proper <buttons>
Form elements grouping
Semantic labels
Zero-out margins and paddings

(This is a common practice. In the end it is always easier to maintain your styles when you define all margins and paddings manually, instead of relying on default values, inconsistent from browser to browser.)
More styling for form elements
List or radio-buttons should be actually lists, for semantics
Let's attach colons to labels automatically
Better to define font-size in relative units
Misc changes