How to make the div not larger than inside content?
You want a block element that has what CSS calls shrink-to-fit width and the spec does not provide a blessed way to get such a thing. In CSS2, shrink-to-fit is not a goal, but means to deal with a situation where browser "has to" get a width out of thin air. Those situations are:
absolutely positioned element
when there are no width specified. I heard they think of adding what you want in CSS3. For now, make do with one of the above.
The decision not to expose the feature directly may seem strange, but there is a good reason. It is expensive. Shrink-to-fit means formatting at least twice: you cannot start formatting an element until you know its width, and you cannot calculate the width w/o going through entire content. Plus, one does not need shrink-to-fit element as often as one may think. Why do you need extra div around your table? Maybe table caption is all you need.
There are two better solutions
Out of these two display:table; is better, because display: inline-block; adds an extra margin.
For display:inline-block; you can use the negative margin method to fix the extra space