Revert "fix: Templates css classes of Slider independently of each other."

See merge request !12

This reverts commit c0b226c3

refactor: Promoslider background apperance for preloaded image improved.
package-portfolio#46

feat: Promoslider Wallpaper (2Content) has load optimized image from first slide to avoid flashing background while loading.
fix: Avoid loading to small images on mobile (Promoslider Wallpaper).

fix: Do not assign Site in Flag.html file. Avoid Uncaught Error: Call to a member function getId() on bool.

refactor: Code style in constructor.