On mobile-width browsers the conversation column and bottom composer could
be forced wider than 100vw: long markdown (URLs, branch names, file paths),
fenced code, and tables stretched the prose container, and the thread scroll
area let the overflow bleed horizontally (#4693).
Add a pure-CSS containment safety net in globals.css:
- .markdown-content gets min-width:0, max-width:100%, overflow-wrap:anywhere
so long tokens wrap instead of stretching the column.
- long links and inline code break rather than overflow.
- fenced/pre blocks and markdown tables scroll inside their own box.
- the thread scroll column clips residual horizontal bleed (overflow-x:hidden)
while vertical scroll and internal code-block scroll are unaffected.
No component, JS, or agent-loop behavior touched; desktop layout unchanged.
Fixes#4693
Co-Authored-By: Claude <noreply@anthropic.com>
