Media query question

Wondering if there is any way I can use a media query to construct a new window or tab url if the user is accessing via mobile, versus a modal pop-up if the user is accessing via monitor. I’ve tried eight gazillion different modal window plugins and css/js/html to get the content to work on a phone; unfortunately the content for the modal window was provided by a government agency with strict instructions not to reformat, and it just doesn’t work in a mobile modal popup. Also, the url content is updated with numbers via javascript, so that needs to work too. Advice?