I think you should make a new thread rather than using this one, but multiple colours works fine for me.
e.g.
PHP Code:
FormatEx(C_Buffer, sizeof(C_Buffer), "\t<font size='20'><font color='#FFFFFF'>WHATEVER<font color='%s'>HELLO</font></font><b>\n", C_Hex);
FormatEx(C_Buffer, sizeof(C_Buffer), "%sTime: <font color='%s'>%s</font>", C_Buffer, C_TimeColour, C_Time);
PrintHintText(client, C_Buffer);