Overflow fix; Minor css fixes

Overflow fix:
- Added a new container into which the 3d image is rendered.
- Removed my3dcontent border from css and added it in a script, which
also resizes the element accordingly

Minor css fixes:
- Stylistic adjustment for various elements
- Separation of most css from html

Other:
- Modified css and css links, so that jquery css comes first and is later customised by the custom css