Zooming left the page filling four fifths of the window, and less as the
zoom went up: at 1.6 it sat in the left three fifths with the rest of the
window empty.
body carried width:calc(100%/zoom). Under CSS zoom a percentage already
resolves against the containing block in the zoomed element's own units,
so 100% is the full width and dividing it again shrank the page by the zoom
a second time. A block fills its container without being told to, so the
declaration is gone. Viewport units are the exception -- dvh does not know
about zoom -- which is why the height still has to be divided back out.
Measured at 1.25, 1.6 and 2: body is exactly the window's 2275 by 1427 in
each, and the document overflows by nothing in either direction. The first
time round only the overflow was checked, which a page that under-fills
passes just as happily as one that fits.
Co-Authored-By: Claude Opus 5 <noreply@anthropic.com>
Ray Slakinski
aa91b457bb