As announced in the last digest, we will be making extensive changes to the Goobi viewer core in the coming months. Specifically, we want to implement a theme for a project whose target group is equally divided between Arabic and English as their mother tongue. However, the languages have different reading directions. Accordingly, the entire theme should be mirrored when the language is changed. To achieve this goal, XHTML structures have to be adapted and CSS instructions have to be changed to newer concepts such as CSS Grid and Flexbox. Concepts that are considered obsolete, such as floats, are removed. Furthermore, individual solutions must be developed, for example for absolutely positioned elements or arrows. An example of an absolutely positioned element is the flag "Add to watchlist" above a thumbnail in the search hit list. Arrows can be found, for example, in the full-screen display at the top right to exit or below to expand and collapse the sidebar.