Sub menu drop down in Wordpress - php

Question

I have hidden my sub menu, and added css to show the sub menu drop down when hovering over the parent menu item.
What I would like to do is have the sub menu drop down when the parent menu button is "clicked" instead of when it is "hovered" over.
My css is:
.sub-menu {
display: none;
}
.shiftnav ul li:hover > ul {
display: block; /* show sub menus when hovering over a parent */
}

Answer 1

I Made and Example
Here is HTML Codes:
#demo {
margin: 30px 0 50px 0;
font-family: Helvetica Neue, Helvetica, Arial, sans-serif;
}
#demo .wrapper {
display: inline-block;
width: 180px;
margin: 0 10px 0 0;
height: 20px;
position: relative;
}
#demo .parent {
height: 100%;
width: 100%;
display: block;
cursor: pointer;
line-height: 30px;
height: 30px;
border-radius: 5px;
background: #F9F9F9;
border: 1px solid #AAA;
border-bottom: 1px solid #777;
color: #282D31;
font-weight: bold;
z-index: 2;
position: relative;
-webkit-transition: border-radius .1s linear, background .1s linear, z-index 0s linear;
-webkit-transition-delay: .8s;
text-align: center;
}
#demo .parent:hover,
#demo .content:hover ~ .parent {
background: #fff;
-webkit-transition-delay: 0s, 0s, 0s;
}
#demo .content:hover ~ .parent {
border-bottom-left-radius: 0;
border-bottom-right-radius: 0;
z-index: 0;
}
#demo .content {
position: absolute;
top: 0;
display: block;
z-index: 1;
height: 0;
width: 180px;
padding-top: 30px;
-webkit-transition: height .5s ease;
-webkit-transition-delay: .4s;
border: 1px solid #777;
border-radius: 5px;
box-shadow: 0 1px 2px rgba(0, 0, 0, .4);
}
#demo .wrapper:active .content {
height: 123px;
z-index: 3;
-webkit-transition-delay: 0s;
}
#demo .content:hover {
height: 123px;
z-index: 3;
-webkit-transition-delay: 0s;
}
#demo .content ul {
background: #fff;
margin: 0;
padding: 0;
overflow: hidden;
height: 100%;
border-bottom-left-radius: 5px;
border-bottom-right-radius: 5px;
}
#demo .content ul a {
text-decoration: none;
}
#demo .content li:hover {
background: #eee;
color: #333;
}
#demo .content li {
list-style: none;
text-align: left;
color: #888;
font-size: 14px;
line-height: 30px;
height: 30px;
padding-left: 10px;
border-top: 1px solid #ccc;
}
#demo .content li:last-of-type {
border-bottom-left-radius: 5px;
border-bottom-right-radius: 5px;
}
<div id="demo">
<div class="wrapper">
<div class="content">
<ul>
<a href="#">
<li>Lorem ipsum dolor</li>
</a>
<a href="#">
<li>Consectetur adipisicing</li>
</a>
<a href="#">
<li>Reprehenderit</li>
</a>
<a href="#">
<li>Commodo consequat</li>
</a>
</ul>
</div>
<div class="parent">Drop Down Parent 1</div>
</div>
<div class="wrapper">
<div class="content">
<ul>
<a href="#">
<li>Lorem ipsum dolor</li>
</a>
<a href="#">
<li>Consectetur adipisicing</li>
</a>
<a href="#">
<li>Reprehenderit</li>
</a>
<a href="#">
<li>Commodo consequat</li>
</a>
</ul>
</div>
<div class="parent">Drop Down Parent 2</div>
</div>

Answer 2

You can achieve nearly the same thing with li a:first-child:nth-last-child(x) { }.
Here is a quick example. The markup is just your standard nested UL, but note that I have only used one class in the HTML, on the root <ul>. Test this out yourself, add any number of nested lists at any level!