WebKit computes `overflow: visible` on a native select, so a long selected
option (the Telegram Command-mode label) painted past the control and became
scrollable overflow of `.settings-scroll`, whose `overflow-y: auto` makes
`overflow-x` compute to `auto`: Settings > Advanced scrolled sideways in the
desktop shell (+147 / +103 / +53 px at 900 / 1000 / 1100 px windows; Blink
clips). `select.ui-control` now clips its value. The global
`::-webkit-scrollbar` recipe sized only `width` (the vertical bar) since the
initial commit, so every horizontal bar kept the 16-17 px UA thickness with
the accent thumb; it now sizes both axes and paints a transparent corner.
DESIGN.md states that a control never widens its column; the Design System
section of DEVELOPMENT.md names the containment rules and the two open gaps
(the wizard document does not load style.css; standard scrollbar-* properties
opt an element out of the webkit recipe on Blink). Two static pins in
tests/test_web_typography_static.py and one WebKit browser test with a
synthetic extension form keep the class closed.
