Created attachment 464888 [details] Here the child UL should be shown immediately to the right of the parent The output height of the child element is based on display: grid, although it should be based on the column-count value based on the position of the parent
<rdar://problem/105160013>
Created attachment 464903 [details] Test reduction It looks like WebKit incorrectly (static) position the out-of-flow block level box when it's inside a multicolumn context.