The projection toggle and the zoom toolbar share the top-right corner. The toolbar
was pinned at a literal top:34px, a number that was correct when it was chosen:
the toggle then measured 74x23 and ended at y=31, which this panel's own comment
records as a live measurement. A later accessibility fix gave the toggle
min-height:24px for WCAG 2.5.8. Nothing in this shadow root sets box-sizing
globally -- it appears exactly once, on the legend -- so 24 was a CONTENT height
and the rendered box became 24 plus 8 padding plus 2 border = 34px. Sitting at
top:8 it now ended at y=42 and ran 8px into the toolbar, which has z-index 10
against the toggle's 3 and so drew straight over it.
Nobody did anything careless. A correct fix to one control broke another because
the agreement between them was a magic number living in the other rule, where the
person changing the first had no reason to look.
So the toggle gets box-sizing:border-box, which makes 24 mean twenty-four and
keeps it a legitimate 24px touch target, and the toolbar's offset is now
calc(--rd-proj-top + --rd-proj-h + --rd-ctl-gap). The relationship is stated once,
on the element that owns it, and both the desktop rule and its mobile restatement
read it. Changing the toggle's size now moves the toolbar by construction.
The check computes the toggle's rendered height from its own declarations the way
a browser does, honouring box-sizing, rather than asserting either number --
restating 34 here would have rebuilt the same trap one file further away. Run
against the code as it stood before this commit it reports the overlap and its
exact size. It also requires the toolbar to DERIVE its offset, because a literal
that is correct today is the precise shape of this bug.
