You might also want to replace the nightfall _FetishStyle.xml with the one from Classic. That should handle everything except colors applied directly to each window. To change the blue titles, you'll need to do a search and replace on each file. Nightfall titles are typically "#88CCFF" with Classic being "F0D040". Other color conversions you may want to do are:
Code:
Nightf Classic
AltBG: 112233 332211
BGfill: 221128 282211
Selects: 334455 4A404A
Input: CCCCFF F0E0DD
InputSel: 8866CC CC8866
Titlesub: 8899FF FBF1D9
Category: DDCCFF F0D080
TextEm1: CDCDFF FFDDBB
TextEm2: CCDDFF FFDDCC
TextEm3: CCFFFF EBDEAA
SubItem: AADDFF FFDDAA