Expand and collapse responsive menu - html

Question

What is the best way I can make this menu default collapse when at a mobile size and use a toggle to collapse and expand.
I would prefer this to be CSS only but am unsure how to do it.
This is the source I am working from.
http://www.script-tutorials.com/demos/335/index.html
/* common and top level styles */
#nav span {
display: none;
}
#nav, #nav ul {
list-style: none outside none;
margin: 0;
padding: 0;
}
#nav {
background-color: #F5F5F5;
border-bottom: 5px solid #333333;
float: left;
margin-left: 1%;
margin-right: 1%;
position: relative;
width: 98%;
}
#nav ul.subs {
background-color: #FFFFFF;
box-shadow: 1px 1px 5px rgba(0, 0, 0, 0.2);
color: #333333;
display: none;
left: 0;
padding: 2%;
position: absolute;
top: 54px;
width: 96%;
}
#nav > li {
border-bottom: 5px solid transparent;
float: left;
margin-bottom: -5px;
text-align: left;
-moz-transition: all 300ms ease-in-out 0s;
-ms-transition: all 300ms ease-in-out 0s;
-o-transition: all 300ms ease-in-out 0s;
-webkit-transition: all 300ms ease-in-out 0s;
transition: all 300ms ease-in-out 0s;
}
#nav li a {
display: block;
text-decoration: none;
-moz-transition: color 450ms ease-in-out 0s, background-color 450ms ease-in-out 0s;
-ms-transition: color 450ms ease-in-out 0s, background-color 450ms ease-in-out 0s;
-o-transition: color 450ms ease-in-out 0s, background-color 450ms ease-in-out 0s;
-webkit-transition: color 450ms ease-in-out 0s, background-color 450ms ease-in-out 0s;
transition: color 450ms ease-in-out 0s, background-color 450ms ease-in-out 0s;
white-space: normal;
}
#nav > li > a {
color: #333333;
display: block;
font-size: 1.3em;
line-height: 49px;
padding: 0 15px;
text-transform: uppercase;
}
#nav > li:hover > a, #nav > a:hover {
background-color: #F55856;
color: #FFFFFF;
}
#nav li.active > a {
background-color: #333333;
color: #FFFFFF;
}
/* submenu */
#nav li:hover ul.subs {
display: block;
}
#nav ul.subs > li {
display: inline-block;
float: none;
padding: 10px 1%;
vertical-align: top;
width: 33%;
}
#nav ul.subs > li a {
color: #777777;
line-height: 20px;
}
#nav ul li a:hover {
color: #F55856;
}
#nav ul.subs > li > a {
font-size: 1.3em;
margin-bottom: 10px;
text-transform: uppercase;
}
#nav ul.subs > li li {
float: none;
padding-left: 8px;
-moz-transition: padding 150ms ease-out 0s;
-ms-transition: padding 150ms ease-out 0s;
-o-transition: padding 150ms ease-out 0s;
-webkit-transition: padding 150ms ease-out 0s;
transition: padding 150ms ease-out 0s;
}
#nav ul.subs > li li:hover {
padding-left: 15px;
}
/* responsive rules */
#media all and (max-width : 980px) {
#nav {
display: none;
}
#burger:hover #nav {
display: block;
}
#nav > li {
float: none;
border-bottom: 0;
margin-bottom: 0;
}
#nav ul.subs {
position: relative;
top: 0;
}
#nav li:hover ul.subs {
display: none;
}
#nav li #s1:target + ul.subs,
#nav li #s2:target + ul.subs {
display: block;
}
#nav ul.subs > li {
display: block;
width: auto;
}
}
<ul id="nav">
<li>Home</li>
<li>Menu 1
<span id="s1"></span>
<ul class="subs">
<li>Header a
<ul>
<li>Submenu x</li>
<li>Submenu y</li>
<li>Submenu z</li>
</ul>
</li>
<li>Header b
<ul>
<li>Submenu x</li>
<li>Submenu y</li>
<li>Submenu z</li>
</ul>
</li>
</ul>
</li>
<li class="active">Menu 2
<span id="s2"></span>
<ul class="subs">
<li>Header c
<ul>
<li>Submenu x</li>
<li>Submenu y</li>
<li>Submenu z</li>
</ul>
</li>
<li>Header d
<ul>
<li>Submenu x</li>
<li>Submenu y</li>
<li>Submenu z</li>
</ul>
</li>
</ul>
</li>
<li>Menu 3</li>
<li>Menu 4</li>
<li>Menu 5</li>
</ul>

Answer 1

I've wrapped the navigation in a div. Added a button and am toggling the navigation on and off when at a mobile size. As well as hiding the burger button when at full width.
<div class="nav-bar">
<div id="burger">
<input type="button" data-name="show" value="Toggle" id="toggle">
</div>
<!--rest of navigation follows here-->
</div>
<script>
$(document).ready(function () {
$("#burger").click(function () {
if ($(this).data('name') == 'show') {
$("#nav").animate({
height: '0px'
}).hide()
$(this).data('name', 'hide')
} else {
$("#nav").animate({
height: '100%'
}).show()
$(this).data('name', 'show')
}
});
});
</script>