Collection for several styling issues

[auge8472]

This is a collection of fixes for issues in the default theme.

[auge8472]

Small fixes for this and that

• The notice of class .caution, that is about warnings, had no background colour.
• Rebuild of a few page blocks from using floats to using flexboxes or grids.
• use box-sizing: border-box; for all elements, computing box sizes is far more intuitive with border-box than with the default value content-box.
• serveral fixes and tweaks for elements in the currently existing flexboxes and grids to adapt their sizes and positions to different sizes/widths of browser viewports

to be continued

[auge8472]

Support of rtl-languages in the UI

The styling support for languages, which are written from right to left (rtl), is currently terrible. After a long research a far better support is possible. Not only (known to me) properties like text-align: start | end, that can replace left | right in a writing direction agnostic way, are well supported by the browsers but also (for instance) padding-inline-start instead padding-left or padding-right which would shift the starting point of the content in an element in a writing-direction independent manner have a wide (and partially long) browser support (all of the replacement properties have at least two years of support).

[auge8472]

The support of rtl-languages spans now (2024-08-07 16:30 CEST) the page header, the subnavigation below the page header and the page footer.

[auge8472]

Now also the thread trees are rtl-writing-direction aware.

[auge8472]

Added the posting footers, the threaded posting views with their posting headers, the blockquotes and the admin main menu to the sections, that are writing direction aware.

[auge8472]

Reformattings in the admin area are mostly done. Many things changed behind the scene. The UI works now far more writing direction agnostic.

[auge8472]

Positioning of the threads lists in the threades as well as table view and the sidebar resectively the bottombar (the infoboxes) is now done with grids. This made it necessary to introduce an additional box around the threads lists and the infoboxes that is only inserted if the infoboxes are displayed. This is the case for administrators and moderators because of the corresponding toolbox. Furthermore this is the case for forums with boxes for displaying the latest X postings and/or the tag cloud on the overview pages.

An additionaly large change is the move of the ID of the bottombar in the table overview page from #bottombar to #sidebar. The ID of the infobar in the threaded over view view was already #sidebar. The necessary distinction between the table-based and the threaded overview views is done with the classes .table and .threaded in the main-grid-divs (#main-grid).

A third change is an experiment. The infobar on the table-based overview page is now displayed above the thread-overview-table and not below as it has been displayed so far. Changing this back if wished, is a no-brainer.

A last remarkable change in the infobars is the permanent display of the heading of class .sidebar and its change from h3 to h2. This makes it generally accessible, corrects the outline of the document and distinguishes this heading from the h3-headings of the other blocks in the infobars.

[auge8472]

There are certainly still some necessary changes. Nevertheless, I would like to finalise the work for the time being.