Freya comes with a captive portal assistant that tries to help you to login (accept ToS) on public networks (like Wifi in a café, etc.). When you connect to such network, a new window opens with what Freaya thinks is the portal website. Actually, it opens https://elementary.io/ and expects it to be redirected to the portal.
However useful it can be for most people, in some situations you may wish to disable this feature. It is very simple, but difficult to find out. Just run this command:
Some time ago I decided I want to use dark GUI wherever possible, main reason being the fact that “white on black” causes much less strain of the eyes than the other way round. This post contains references to all the different guides, dark themes, software or other related tips I encountered and found useful in some way.
It may look like a lot of work, but if you spend a lot of time on the computer and care about your health, it is definitely worth it.