For the spry menu on the left you can adjust the color by opening the spry_custom.css file, in here look for this style:
.AccordionPanelTab {
background-color: #eeeeee;
border: 0;
border-top: solid 1px white;
padding:10px;
}
It is the background color in here that is the color you see.
The blue color that you see when you go into a category is set via JavaScript so you will not find it in any of the css files. It is located in the js code in your Main.dwt.php template near line 165, here is the exact line of code:
div.setAttribute('style',"background-color:#3375A2; color: white; border-top:0px;");
It is the background color listed here that you need to change.
The color of the text in the spry menu is inherited from the body styling. This is in the common.css file toward the top, look for the color property in here. If you want to add your own custom color for the text you can just add to the .AccordionPanelTab { style, put a color in here.
There is a thread that discusses these settings and has some more info on it here:
showthread.php?t=10430