portable renders a page differently than desktop version

Hello,
I'm using Firefox on my own private machines and I find it runs perfectly.
Now I tried since FF 30 the portable version and I found that pages are rendered differently than Firefox installed versions.
You can reproduce this and see the differences by visiting pages on www.t-online.de.
Here are on multiple pages boxes containing social media bookmarks and also links for printing, mailing and settings. The installed version of Firefox shows these boxes as expected. Only in ff portable these boxes are shown in a strange way.
What please can be the reason? Are some settings wrong?
Kind regards