User-Agent: Mozilla/5.0 (Windows; U; Windows NT 5.1; es-ES; rv:1.9.0.3) Gecko/2008092417 Firefox/3.0.3 Build Identifier: Mozilla/5.0 (Windows; U; Windows NT 5.1; es-ES; rv:1.9.0.3) Gecko/2008092417 Firefox/3.0.3 If we apply the "collapse" value to the "border-collapse" property on a table and either it or its cells have any kind of border, it's positioned according to the grid and not to the space occupied by such border. Is it correct? Or is it just the own Firefox interpretation for the standard? If so, Doesn't it contradict the concepts of positioning and border on CSS? Reproducible: Always Steps to Reproduce: 1. Design a table like the one below: <table> <tbody> <tr> <td>Cell 1</td> <td>Cell 2</td> <td>Cell 3</td> </tr> </tbody> </table> 2. Apply these CSS rules: body { margin: 0px; } table { border-collapse: collapse; border-spacing: 0px; table-layout: auto; } td { border: solid 4px #ff0000; width: 100px; } Actual Results: The table is positioned according to its internal grid, so the half of the border is ignored for this calculation, not causing a correct of push to the adjacent elements. This causes that the table overrides part of any surrounding element. In this case, this makes the document to hide the half of the left and top borders. Expected Results: The external half of the border should be taken into account to calculate the location and push of the table. Opera, Safari and Internet Explorer (all them on a Windows XP platform) renders the table as expected, taking into account the whole border.

I see the thinner left and top border also in older Firefox versions like Firefox 1.

(In reply to comment #0) > If we apply the "collapse" value to the "border-collapse" property on a table > and either it or its cells have any kind of border, it's positioned according > to the grid and not to the space occupied by such border. Is it correct? > That is actually what the spec says. http://www.w3.org/TR/CSS21/tables.html#collapsing-borders