I believe I´ve found a bug.
Default theme, english, no mods.
When I reply to a post, I get a page with the editor and a "Topic summary". In this summary url´s or other very long words don´t break but continues off the screen.
Tested in iPhone, Android, Chrome, Edge and Firefox.
Chrome:
u1.jpg
Edge:
u2.jpg
In standard topic view the url breaks as expected:
u3.jpg
Lol. Another CSS oversight. Add it to the list. :)
https://github.com/SimpleMachines/SMF2.1/pull/7357