I cloned one of the default themes and am trying to modify it for my own use. I'm editing the php and css files and usually I can see the result of my edits right away. However, I am having an issue with the css where the file in the themes/myTheme directory has the correct value but the browser is displaying the old value. Sometimes, I'll do the edit and see the css change right away on a refresh. Then after a half hour or so, the browser will all of a sudden start showing the old layout. I don't have full page caching on. I've tried using different browsers and clearing the browser cache. I don't understand where these old values could be coming from. Any ideas?