Many people are looking just for the center block which can hold feeds titles from diferent sources, formated on one, two, three columns [or more] but they just forget about the colours used on this block.
The colours which I used to draw this block are $bgcolor1, $bgcolor2 which are defined on your theme so if the theme is changed these colours changes also depending of the theme installed.
But sometimes the combination of these two colour[$bgcolor1 used as a background of the table and $bgcolor2 the background of a cell] are just not right and the whole impression is that this block doesn't fit with your theme colours.
If you are really unhappy about this combination [$bgcolor1, $bgcolor2] you can change it to fit your theme better....$bgcolor2 have more impact on apearance;
Open blocks/block-Multiheadlines-center.php and just below the globals line[first line]

add your own colours as bellow