Responsive Nav Quickly Closing once clicked

Responsive Nav Quickly Closing once clicked

Hoping someone can help me out - had to code a responsive menu myself for the first time and the javascript seems to be glitchy or something. It works fine if I don't have the extra query within the slide toggle, but the regular nav menu won't show again once the browser is widened past the mediascreen of 960px. This is what the extra function was added for, but now the mobile menu just opens and quickly quits as soon as you click on it (probably because of that 400 limit - but whyyy?).

Anybody have any advice? You can see it live at ezymarketing.com . Thanks in advance!

Here's my script code for the hidden navigation:

    jQuery(".mobile-trigger").click(function(){
        jQuery("#navigation").slideToggle(400, function() {
            jQuery(this).toggleClass("nav-expanded").css('display', '');
                });
               
    });


And then I have this code within my CSS to style it:

                .mobile-trigger {display:none;
                                 font-size: 22px;
                                 padding-top: 100px;
                                font-weight: bold;
                                color:#64B446;
                                pointer:clicker;}
            @media screen and (max-width: 960px) {   
                               .mobile-trigger {display:block;}
                              
                                #navigation {display:none}
                               
                                div.nav-expanded {
                                     display:block;
                                      }

                #navigation ul {display:block;
                    background: #fff;
                    float:none;
                                        padding-top: 100px;
                }
                #navigation li {
                    border-bottom: 2px solid #60B648;
                }
                #navigation li:last-child {
                    border-bottom: none;
                }           
                .featured-text .element {
                    padding: 0;
                }
                               
            }