Bugfix for browser not understanding calc at all.

(Safari 5.1 for example…)
Old-Safari-Bugfix regarding aligning of links- and imprint-box in wide screen layout.

(Boxes were aligned left and not centered.)
IE fixes

- IE needs an additional "width: 100%" on the tagcloud- and on the links-box, otherwise contents will not wrap.
- IE has different default values for flex-grow and flex-shrink then other browsers. Therefore the tagcloud- and links-box looked like garbage (didn't grow).
Fixed media query.

(Without this fix the widescreen view would be effective, but we would produce a horizontal scrollbar in some cases.)