Creating a dropdown list item menu with CSS only - html

Question

In a section of website I'm working on I have a NAV element that contains three sections: About, Portfolio, Contact. I'm trying to make it so that when you hover over the Portfolio section, a drop down appears allowing you to choose between two other sections, "Writing Samples" and "Photoshop." I am trying to accomplish this using only CSS.
This is my HTML section:
<nav>
<ul>
<li>
<a href="index.html" >About</a>
</li>
<li class="subNav">
<a class="selected" >Portfolio</a>
<ul>
<li>Writing Samples</li>
<li>Photoshop</li>
</ul>
</li>
<li>
Contact
</li>
</ul>
</nav>
And CSS:
nav {
position: absolute;
bottom: 0;
right: 0;
padding: 10px 0;
}
nav ul {
list-style: none;
margin: 0 10px;
padding: 0;
}
nav li {
display: inline-block;
}
nav a {
font-weight: 800;
padding: 15px 10px;
}
nav ul li.subNav ul {
display: none;
}
nav ul li.subNav:hover ul {
display: block;
}
I have reached the point that when I hover over the Portfolio list item, you see the resulting list items "Writing Samples" and "Photoshop", except that it displays these two items as a part of the original unordered list, and moves the "Portfolio" list item above the rest of the items. I would like "Writing Samples" and "Photoshop" to appear vertically under "Portfolio", but I can't quite figure this out with CSS.

Answer 1

This is the basics of it:
nav {
position: absolute;
padding: 10px 0;
}
nav ul {
list-style: none;
;
padding: 0;
}
nav > ul > li {
display: inline-block;
position: relative;
border: 1px solid lightgreen;
/* for demo */
}
nav a {
font-weight: 800;
padding: 5px 10px;
display: block;
}
nav > ul > li.subNav ul {
display: none;
position: absolute;
top: 100%;
left: 0;
white-space: nowrap;
background: pink;
}
nav ul li.subNav:hover ul {
display: block;
}
<nav>
<ul>
<li>
About
</li>
<li class="subNav">
<a class="selected">Portfolio</a>
<ul>
<li>Writing Samples
</li>
<li>Photoshop
</li>
</ul>
</li>
<li>
Contact
</li>
</ul>
</nav>
The parent li is given position:relative to provide positioning context.
The submenu is positioned absolutely, at the bottom of the parent li and aligned left.
Note that I have used the direct child selector > to target only the elements I want to.
Then, since the submenu is too wide to be contained within the parent's width, I added white-space:nowrap so that the text will flow as required.

Answer 2

You have the right idea; the comment tags in the HTML below are used to remove space between the "li" elements.
Instead of using display:none, I use visibility: hidden for S.E.O purposes.
Even though you use position: absolute, you should also use z-index so that menu elements are able to be clicked if they are overlapping other content.
.mm,
.sm {
list-style: none;
}
.mm {
position: relative;
margin: 0px;
padding: 0px;
background-color: #000;
border-bottom: 4px solid red;
}
.sm {
position: absolute;
z-index: 1;
visibility: hidden;
background-color: #000;
border-width: 0px 4px 4px 4px;
border-style: solid;
border-color: red;
}
.mm > li {
display: inline-block;
}
.mm > li > a {
display: inline-block;
padding: 8px;
}
.sm a {
display: block;
padding: 8px;
}
.mm > li > a:hover + .sm,
.sm:hover {
visibility: visible;
}
.mm a {
text-decoration: none;
color: #FFF;
}
.mm a:hover {
text-decoration: underline;
color: yellow;
}
<nav>
<ul class="mm">
<li>AAA</li><!--
--><li>BBB
<ul class="sm">
<li>SUB</li><!--
--><li>SUB</li><!--
--><li>SUB</li>
</ul>
</li><!--
--><li>CCC
<ul class="sm">
<li>SUB</li><!--
--><li>SUB</li><!--
--><li>SUB</li>
</ul>
</li>
</ul>
</nav>
<h1>CSS NAVIGATION</h1>