CSS Pocket Reference, 3rd Edition

Table Arrangement Rules

In general, a table is laid out according to the following principles:

• Each row box encompasses a single row of grid cells. All of the row boxes in a table fill the table from top to bottom in the order they occur in the source document. Thus, the table contains as many grid rows as there are row elements.

• A row group’s box encompasses the same grid cells as the row boxes that it contains.

• A column box encompasses one or more columns of grid cells. Column boxes are placed next to each other in the order they occur. The first column box is on the left for left-to-right languages and on the right for right-to-left languages.

• A column group’s box encompasses the same grid cells as the column boxes that it contains.

• Although cells may span several rows or columns, CSS does not define how that happens. It is instead left to the document language to define spanning. Each spanned cell is a rectangular box one or more grid cells wide and high. The top row of this rectangle is in the row that is parent to the cell. The cell’s rectangle must be as far to the left as possible in left-to-right languages, but it may not overlap any other cell box. It must also be to the right of all cells in the same row that are earlier in the source document in a left-to-right language. In right-to-left languages, a spanned cell must be as far to the right as possible without overlapping other cells and must be to the left of all cells in the same row that come after it in the document source. ...