Drop down menu to hide on click event

Question

How do I hide my menu on a click event

Background

I am using a pure CSS3 menu in a single page application. It works well.

body {
    font: normal .8em/1.5em Arial, Helvetica, sans-serif;
    background: #ebebeb;
    width: 900px;
    margin: 100px auto;
    color: #666;
}
a {
    color: #333;
}
#nav {
    margin: 0;
    padding: 7px 6px 0;
    line-height: 100%;
    border-radius: 2em;

    -webkit-border-radius: 2em;
    -moz-border-radius: 2em;
    
    -webkit-box-shadow: 0 1px 3px rgba(0, 0, 0, .4);
    -moz-box-shadow: 0 1px 3px rgba(0, 0, 0, .4);

    background: #8b8b8b; /* for non-css3 browsers */
    filter:  progid:DXImageTransform.Microsoft.gradient(startColorstr='#a9a9a9', endColorstr='#7a7a7a'); /* for IE */
    background: -webkit-gradient(linear, left top, left bottom, from(#a9a9a9), to(#7a7a7a)); /* for webkit browsers */
    background: -moz-linear-gradient(top,  #a9a9a9,  #7a7a7a); /* for firefox 3.6+ */

    border: solid 1px #6d6d6d;
}
#nav li {
    margin: 0 5px;
    padding: 0 0 8px;
    float: left;
    position: relative;
    list-style: none;
}
/* main level link */
#nav a {
    font-weight: bold;
    color: #e7e5e5;
    text-decoration: none;
    display: block;
    padding:  8px 20px;
    margin: 0;
    -webkit-border-radius: 1.6em;
    -moz-border-radius: 1.6em;
    text-shadow: 0 1px 1px rgba(0, 0, 0, .3);
}
/* main level link hover */
#nav .current a, #nav li:hover > a {
    background: #d1d1d1; /* for non-css3 browsers */
    filter:  progid:DXImageTransform.Microsoft.gradient(startColorstr='#ebebeb', endColorstr='#a1a1a1'); /* for IE */
    background: -webkit-gradient(linear, left top, left bottom, from(#ebebeb), to(#a1a1a1)); /* for webkit browsers */
    background: -moz-linear-gradient(top,  #ebebeb,  #a1a1a1); /* for firefox 3.6+ */

    color: #444;
    border-top: solid 1px #f8f8f8;
    -webkit-box-shadow: 0 1px 1px rgba(0, 0, 0, .2);
    -moz-box-shadow: 0 1px 1px rgba(0, 0, 0, .2);
    box-shadow: 0 1px 1px rgba(0, 0, 0, .2);
    text-shadow: 0 1px 0 rgba(255, 255, 255, .8);
}
/* sub levels link hover */
#nav ul li:hover a, #nav li:hover li a {
    background: none;
    border: none;
    color: #666;
    -webkit-box-shadow: none;
    -moz-box-shadow: none;
}
#nav ul a:hover {
    background: #0399d4 !important; /* for non-css3 browsers */
    filter:  progid:DXImageTransform.Microsoft.gradient(startColorstr='#04acec', endColorstr='#0186ba'); /* for IE */
    background: -webkit-gradient(linear, left top, left bottom, from(#04acec), to(#0186ba)) !important; /* for webkit browsers */
    background: -moz-linear-gradient(top,  #04acec,  #0186ba) !important; /* for firefox 3.6+ */

    color: #fff !important;
    -webkit-border-radius: 0;
    -moz-border-radius: 0;
    text-shadow: 0 1px 1px rgba(0, 0, 0, .1);
}
/* level 2 list */
#nav ul {
    background: #ddd; /* for non-css3 browsers */
    filter:  progid:DXImageTransform.Microsoft.gradient(startColorstr='#ffffff', endColorstr='#cfcfcf'); /* for IE */
    background: -webkit-gradient(linear, left top, left bottom, from(#fff), to(#cfcfcf)); /* for webkit browsers */
    background: -moz-linear-gradient(top,  #fff,  #cfcfcf); /* for firefox 3.6+ */

    display: none;
    margin: 0;
    padding: 0;
    width: 185px;
    position: absolute;
    top: 35px;
    left: 0;
    border: solid 1px #b4b4b4;
    -webkit-border-radius: 10px;
    -moz-border-radius: 10px;
    border-radius: 10px;
    -webkit-box-shadow: 0 1px 3px rgba(0, 0, 0, .3);
    -moz-box-shadow: 0 1px 3px rgba(0, 0, 0, .3);
    box-shadow: 0 1px 3px rgba(0, 0, 0, .3);
}
/* dropdown */
#nav li:hover > ul {
    display: block;
}
#nav ul li {
    float: none;
    margin: 0;
    padding: 0;
}
#nav ul a {
    font-weight: normal;
    text-shadow: 0 1px 1px rgba(255, 255, 255, .9);
}
/* level 3+ list */
#nav ul ul {
    left: 181px;
    top: -3px;
}
/* rounded corners for first and last child */
#nav ul li:first-child > a {
    -webkit-border-top-left-radius: 9px;
    -moz-border-radius-topleft: 9px;
    -webkit-border-top-right-radius: 9px;
    -moz-border-radius-topright: 9px;
}
#nav ul li:last-child > a {
    -webkit-border-bottom-left-radius: 开发者_JAVA百科9px;
    -moz-border-radius-bottomleft: 9px;
    -webkit-border-bottom-right-radius: 9px;
    -moz-border-radius-bottomright: 9px;
}
/* clearfix */
#nav:after {
    content: ".";
    display: block;
    clear: both;
    visibility: hidden;
    line-height: 0;
    height: 0;
}
#nav {
    display: inline-block;
}
html[xmlns] #nav {
    display: block;
}
* html #nav {
    height: 1%;
}

CSS3 Dropdown Menu by Web Designer Wall

Assuming your question is "what do I need to do with the Javascript?", one of the easiest ways to hide the dropdown is to use a framework, such as jQuery. Using jQuery allows you to write something like (untested):

$('#parent_li').click(function(){
    $('#child_li').slideToggle('slow');
});

Which will toggle the visibility state of the list item's child list. In this case, using a slow slide animation, but there are other animation types you can use.

Kindly check if the below link helps

<nav role="navigation">
<div id="menuToggle">
<!--
A fake / hidden checkbox is used as click reciever,
so you can use the :checked selector on it.
-->
<input type="checkbox" />

<span></span>
<span></span>
<span></span>

<ul id="menu">
  <a href="#"><li>Home</li></a>
  <a href="#"><li>About</li></a>
  <a href="#"><li>Info</li></a>
  <a href="#"><li>Contact</li></a>
  <a href="https://erikterwan.com/" target="_blank"><li>Show me more</li> 
  </a>
 </ul>
 </div>
</nav>

https://codepen.io/erikterwan/pen/EVzeRP