In the collapsed-border model of tables, the width of the table is defined as the width off all cell-widths, plus the sum of all widths of the inner borders, plus 1/2 of the left outer border and 1/2 of the right outer border. This very annoying fact leads to the predicament, that the border extends beyond the margins, if the margin happens to be less then 1/2 the border. Now, in my opinion it would have been necessary to think of this before the W3C made this spec and include a mechanism similar to what I propose in the attached image, an automatic addition to the defined borders that leads to the border always being fully included inside the margins. But because I very much doubt that such an extension would be made because some half-grown web-designer feels that the current specs lack some thought in this case, here is another thing: I’ve positioned a div with a ul and li inside, formatted via css to be an inline-table, a table-row and table-cells respectively, at top:85px and right:0px. The cells inside this table (border-collapse:collapse) all have a border of 1px. Because of what I assume is a rounding phenomena, the top border of the table-cells appears at top:84px – one pixel too far up -- whereas the right border of the right-most cell appears at right:0px. This can’t be right by any spec. Either the border should extend over the margin in both cases, and then appear to be drawn at top:84 and right:-1 or it should lead to both borders being drawn inside the margin and then have the element be drawn at the expected position, a result I would expect, since as far as I know, 0.5 is usually rounded up.

YUI: Opera 7.54 does it in the way proposed in the testcase.

*** This bug has been marked as a duplicate of 155955 ***