I believe the file browser always uses the system font and that it's colors are hard coded in core/gui_fselect.c and cannot be changed unless you are up to modifying the source code and recompiling it. Experimenting with different colors shouldn't be overly difficult, changing the font probably much more so.
I find the OSD font too small for my eyes to read comfortably and I want to increase the size of the system font.
In core/gui_fselect, which are the right bits to edit?
These?- //-------------------------------------------------------------------
#define HEAD_LINES 1
#define BODY_LINES 10
#define FOOT_LINES 1
#define HEAD_FONT_LINES HEAD_LINES * FONT_HEIGHT
#define BODY_FONT_LINES BODY_LINES * FONT_HEIGHT
#define FOOT_FONT_LINES FOOT_LINES * FONT_HEIGHT
#define NAME_SIZE 15 // "FILENAME123 "
#define SIZE_SIZE 7 // "1000 b|M|G"
#define TIME_SIZE 14 // "01.01'70 00:00"
#define NAME_FONT_SIZE NAME_SIZE * FONT_WIDTH
#define EXTE_FONT_SIZE EXTE_SIZE * FONT_WIDTH
#define SIZE_FONT_SIZE SIZE_SIZE * FONT_WIDTH