The themed WebKit scrollbar skin keeps a wide table's horizontal bar
permanently painted. Chromium never repaints state-conditioned scrollbar
styles (hover-conditioned ::-webkit-scrollbar* rules and :hover
scrollbar-color changes both compute but never reach the painted bar,
measured headed and headless), so the hover reveal toggles overflow-x
itself: hidden at rest with a padding-bottom matching the themed bar
height, auto on hover or keyboard focus with the padding released — the
appearing bar exactly replaces the padding and nothing below shifts.
Resting hidden overflow drops Chromium's implicit scroller focusability,
so wide wrappers carry an explicit tabindex for arrow-key scrolling.
Markdown tables were always rendered at natural width, so anything wider
than the 748px message column could only be read through horizontal
scrolling. Following the deepsuite chat TableWrapper treatment: tables
under four columns (and any table inside a blockquote) now fill the column
and wrap cell text down to the cells' minimum readable width, while
four-or-more-column tables keep their natural width behind the wrapper's
horizontal scroll and carry the stable md-table-wide hook. The chat
transcript widens hooked tables past the message column with a pure-CSS
container-query breakout (100cqw against ChatView's scroll container
standing in for deepsuite's JS-measured list width), keeping the table
content aligned with the message column and clamping to neutral when the
transcript is narrower than the column.
_Kerman