浮动块级元素：是否需要设置宽度，如果是，如何？

Say I have textboxes, dropdownlists and submit buttons. They are all inline-elements. Which means that "officially" margin, padding, width and height properties should be ignored (in practice not really). If I were to go the right way to set the height to a button I would write something like display:block and then define the height. But there are considerations that a block level element would expand itself unexpectedly so I'd better set its width to some fixed value. The problem is that I don't know its width since it can be dynamically defined upon the text of the button.Say I have textboxes, dropdownlists and submit