Trying to create a sloppy rectangle without clip path

I'm trying to create a box with the top border skewed, the right border skewed to the left, the left to right and the bottom should stay straight. It need to look like this:

I could accomplish this using a clip-path but I want to have compatibility for more browsers (like older browsers, i.e & opera).

I thought maybe using inline SVG but I think that in SVG the height must be specified and I want that the height of the box will defined by it's content (dynamic).