Minor issues in Element Dark Theme

[kefiiris]

In the Element Dark Theme, I have observed 5 issues that make the design a bit non uniform. These issues are not present on Element itself.
In element black, issue 1, 3 and 5 are present.
In element light, all issues except 1 are present. 2, 3 and 4 are less prominent due to only slight colour difference.

1. The unread counter is close to invisible.
   

2. There is a black line between the Navigation bar and the bottom of the app.
   

3. The colors of the statusbar and the titlebar of a room do not match.
   

4. The colors of the navigation bar and the backdrop of the chat area do not match.
   

5. There are 2 element-style cyan coloured bars on the first loading page of the app.
   

[SpiritCroc]

I don't really recommend using the Element theme since it's largely untested from my side - the settings is just there because it didn't hurt to keep it in. I'm open to contributions if anybody wants to take care of these issues though, if their changes don't cause merge conflicts (i.e., do not mess with any upstream theming but only touch downstream modifications).