JQueryUI in chrome extension content script

After putting jquery-ui (css and js) and jquery in the manifest, I can use jq ($) selectors, however jquery-ui seems to be unavailable. For example, I'm trying to insert a resizable div in a content-script (content_script.js):

var $div = document.createElement('div');
$div.id = 'divId';
$div.innerHTML = 'inner html';
$("body").append($div);//works without error
$("#divId").css("background-color","yellow");//works
//doesn't give resizable handles, however works in a regular html file:
$("#divId").resizable();
//however this also has issue:
document.getElementById("divId").style.resize = "both";

      

        
        
        
      

    

manifest:

"css":["jquery-ui.css"],
"js": ["jquery-ui.js","jquery.js","content_script.js"]