What has been changed?
Secondly, I added some support for debugging (thanks to Peter Reid for this), in case you want to use the source code and modify it yourself:
The third and last change is the addition of an additional stylesheet, that can be used for the Custom CSS Link property of the web part:
To use this stylesheet, modify your target web part’s properties, and change the Custom CSS Link property to <SiteCollectionPath>/Office365RSSWebPartClientSide/WhiteBlue.css (replace <SiteCollectionPath> with the correct URL of your site collection where you deployed the web part to, e.g. /sites/finance ; for the root site collection, simply use /Office365RSSWebPartClientSide/WhiteBlue.css;).
Download the Web Part