[calorie]

Do you mean in the "code" box? IIRC the color of the code text is the same color as the text in the post, so you might consider changing the background color of the code box instead. If you want to do that, this should be the related CSS:

blockquote.preview .bbcode_container div.bbcode_code,
blockquote.preview .bbcode_container pre.bbcode_code {
	margin:0;
	padding:6px;
	border:1px inset;
	text-align:{vb:stylevar left};
	overflow:auto;
	direction:ltr;
	background:{vb:stylevar content3_background.backgroundColor} {vb:stylevar content3_background.backgroundImage} repeat-x;
	/*height:{vb:stylevar bbcode_codeheight};*/
	font-size:12px;
}