TWO CHANGES, and the first is an argument I got wrong.
The frame was scaled to fit the panel with a transform. That made the preview change apparent size as
the panel was dragged, so the same page looked different at every panel width and nothing could be
judged against anything. A preview is 1:1 or it is not a preview.
So it stays at the device's real width and OVERFLOWS when there is not room — a scrollbar rather than a
lie. The width was never negotiable anyway: the site's media queries answer it, so a frame given the
panel's width renders the tablet layout and calls it desktop. What changes is only what happens when it
does not fit, and scrolling is the honest answer.
THE MEASURE, as two fixed lines and a width in pixels.
The page is held to max-w-7xl and centred, so on a wide screen the content stops well short of the
window and nothing says where. That is invisible until something is placed against the edge and turns
out to be in the wrong place — which is the moment it becomes expensive.
Fixed rather than absolute, so they stay while the page scrolls; a guide that scrolls away is a guide
for the top of the page only. Not drawn at all when the column IS the full width, because two lines
against the window edges are noise claiming to be information.
One more site marker: data-content-column. Four attributes now, still no behaviour.
Co-Authored-By: Claude Opus 5 (1M context) <noreply@anthropic.com>