It would be awesome if someone would have replied to this.  I am having the same issue and am going nuts trying to figure it out.

I went back and looked at my old code.  I had enabled the custom input field name and IDs under the Core Form Admin/Email Options section because I was integrating with PayPal, so some of my field ids are non-standard in this css code snippet.

You need to modify the active cforms.css file.

Changing a field width is the easiest thing to do since it is the width command. 

To make fields appear on the same line you need to use float left.  To cause a line break to appear, you need to use the clear left command, but it affects the next element, not current element.

You need to use the display none command to hide labels if you want adjacent fields without a label.

/* next three fields appear on the same line */

#cforms4form.cform #amount_2 {

width:60px;

}

#cforms4form.cform #Field-2 {

width:30px;

margin-left: 5px;

}

/* the next field after this one will be on next line */

#cforms4form.cform #Field-3 {

width:70px;

clear:left;

}

/* The next fields appear on the same line, but the second field label does not appear */

#cforms4form.cform #li-4-11 {

float: left;

}

#cforms4form.cform #li-4-12 {

float: left;

display: none;

}