v155 · margin-trim
The workarounds it retires
Four techniques stylesheets have used to stop the first and last child pushing against the container, running against the same markup. The interesting test is the checkbox: hide the first child, the way a conditional component does. Both selector-based fixes fail it — including the owl selector, which is usually held up as the robust one.
The same list, five ways
Each amber band is the container's 16px padding. A lane is correct when the visible first and last children sit flush against it — measured, not eyeballed.