Absolutely positioned panel ignores top inset: inherited align-self start

A floating panel with position:absolute, top:181px and bottom:12px rendered at top:0 and as tall as its whole content (6000px) in current Chrome. getComputedStyle showed top:181px and position:absolute, and even an inline !important top changed nothing, while an explicit height worked. Cause: an older base rule gave the element align-self:start (it used to be a sticky grid item). Browsers now apply CSS Box Alignment to absolutely positioned boxes, so align-self:start sizes the box to fit its content, and when that overflows the inset-modified containing block it is shifted back inside the containing block, to the top. Fix: align-self:stretch (or normal) on the positioned element. Diagnose by checking computed align-self/justify-self when top/bottom seem ignored.