The DIV 'tableauPlaceholder' defines the width. Writing Embed Code
There's a bunch of people who've achieved responsive behavior or similar before here on the forums. It's definitely worth searching in the first instance - https://community.tableau.com/search.jspa?q=embed+responsive
Can you define "doesn't work properly" ?
1. I usually set the dashboard size to a few pixels less than the iframe (or whatever embed method you are using) is set to.
2. Not a "proper" responsive design, but I have seen some smart CSS code which chose which dashboard to render ... and there's always version 10 in a few weeks