How to override subtheme settings (inheritance)? I am having some difficulty overwriting my subtheme code using my own theme.css file (located in sites>all>themes). I can find the code that results in the display of whichever css style property I'm trying to change (e.g., font-family in the header region) easily, using the chrome DevTool, but when I go to target that area in my own css file it seems not to have any effect on the display. Is there any general methodology with which I can go about inheriting my adjustments to the theme styles? FYI I have renamed my subtheme's files so that is not the issue.

Any help would be wonderful.
Assuming you've cleared the cache and all that before trying to inspect any changes, it sounds like your base theme (the theme you've based your sub-theme on) is one of those themes where the configuration is for a large part done by means of the administrative interface. This means that edits done to the .css fileshave no effect, as they're overridden by settings the administrative interface.

A number of popular themes has this property, including the Adaptive Themes family and Omega 3.

To check out if this is the case, navigate to Administration » Appearance » Settings for your theme (or sub-theme).  If there is a lot of settings for fonts, etc., hacking the .css files will not help much and you need to use the administrative interface for styling.