Hi,
On http://docs.moodle.org/dev/Themes#CSS it states:
"Every plugin can have its own styles.css file. This file should only contain the required CSS rules for the module and should not add anything to the look of the plugin such as colours, font sizes, or margins other than those that are truly required."
And yet the contents of /mod/resource/styles.css in Moodle 2.3 and 2.4 has:
.path-mod-resource .resourcecontent {text-align: center;}
.path-mod-resource .resourcedetails {font-size: 0.8em; color: #555;}
.resourcelinkdetails {font-size: 0.8em; color: #555;}
This I think is a 'bug' in more respect to colour. I know that my Collapsed Topics plugin has colour but that is a part of its functionality and is customisable by the user through the UI.
I do have a workaround to this through:
$THEME->plugins_exclude_sheets = array(
'mod' => array('resource')
);
Thanks to the information provided on: https://moodle.org/mod/forum/discuss.php?d=220347
Therefore I consider that it should be up to the theme to decide.
Cheers,
Gareth