Improve digest formatting

When writing a post with quite many tags, I stumbled over a non-efficient formatting of the "digest" box (summarizing categories, tags, date, authors...)

Specifically, the author's column often gets squeezed a lot.

Propose to change the digest formatting slightly (remove inline-flex, and allow 2 columns also on phone as this fits in practically all cases)

Review:

• Exemplary blog post: old vs new
• Overview list: old vs new
• I cannot find any glitches/worse formatting elsewhere.

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To do:

• Let review
• If accepted, rebase to master
• merge