I created a form a while back and included an entry like this:
'#size' => 10
in several text fields of the form. Especially useful when you add a suffix:
'#field_suffix' => 'Something'
But that would not do anything... I looked at the output of the form and it looked 100% correct. In other words, the input tag had its size="10" properly set. So the next step was to find whether some CSS code would be in the way.
You bet! The node.css file includes the following: