解决方法
Ian Hixie在这里详细解释：
The mystery of why only four properties apply to table columns.相关报价：
The colour of text is dependent on the ‘color’ property of its element. Unless specified,the ‘color’ property (basically) defaults to ‘inherit’,which means “take the value of the parent element”.
So for some text in a cell,the colour is determined by the ‘color’ property of the cell,which is taken from the row,which is taken from the table,which is taken from the table’s parent,and so on.
What about the column? Well,the column isn’t one of the cell’s ancestors,so it never gets a look-in! And therein lies the problem.
