jquery - Hide a specific H2 id using javascript or CSS -

we're looking zendesk our support site it's not customizable. i'm trying remove specific text page using widgets function (which can created in javascript or css).

i'm trying hide following h2 tag while displaying page:

<h2 id="search_box">knowledge base &amp; forums</h2> 

i've tried following css:

.search_box {     display: none; } 

but doesn't seem work. i'm not great either css or javascript , don't know when these widgets run, assume i'm doing wrong in terms of accessing element on page.

i've been able hide text using following combination of javascript , css codes, doesn't need because hide part of page has text in it:

javascript:

$j('h2:contains(knowledge base & forums)').addclass('forumtitle'); 

css:

.forumtitle {     display: none; } 

thanks help!

#search_box {     display: none; } 

. classes, # ids