I haven't used the template. But in my understanding, the changes ought to take place on ./dark/views/default/css.php

After you modify any css.php file, run the upgrade script to make the changes appear.

Upgrade script: http://SITEURL/upgrade.php

If you'd like to know the CSS classes of an element, using Firebug could be useful.

@Shouvik:  Ahhh thanks I did not know about the upgrade script. i'll go back and start trial and error again from the beginning and also give Firebug a try

Finally got it working. Thanks all for the help! the upgrade script was what I was missing. Firebug was also a nice helper, just verified what I thought from the beginning (that the style i was supposed to be editting was collapsable_box_content)

For anyone else who may be having this same problem:

I edited the file: ./dark/views/default/css.php 

 .collapsable_box_content {
        padding: 10px 0 10px 0;
        margin:0;
        height:auto;
color:#fff;
        -moz-border-radius-bottomleft:8px;
        -moz-border-radius-bottomright:8px;
        -webkit-border-bottom-right-radius:8px;
        -webkit-border-bottom-left-radius:8px;
        border-left: 1px dashed #3C90B8;
        border-right: 1px dashed #3C90B8;
        border-bottom: 1px dashed #3C90B8;
}

I changed the color to #000000; so it now reads:

.collapsable_box_content {
        padding: 10px 0 10px 0;
        margin:0;
        height:auto;
color:#000000;
        -moz-border-radius-bottomleft:8px;
        -moz-border-radius-bottomright:8px;
        -webkit-border-bottom-right-radius:8px;
        -webkit-border-bottom-left-radius:8px;
        border-left: 1px dashed #3C90B8;
        border-right: 1px dashed #3C90B8;
        border-bottom: 1px dashed #3C90B8;
}

Then I ran the upgrade script. Text color worked.