CSS navigation with cut-out notch as marker - css

Question

I know I have seen this somewhere before, but I am trying to create a black fixed navbar with a marker that is transparent cut-out triangle. I need help getting the triangle cut-out to be transparent to the background, so when you scroll the page, you can see through to the content beneath:
I have a standard list/anchor navigation with a javascript to move the .current class depending upon the page section:
<div class="navbar">
<ul>
<li class="current"><a>home</a></li>
<li><a>products</a></li>
<li><a>services</a></li>
<li><a>contact us</a></li>
</ul>
</div>
styled with the following CSS:
.navbar {
width: 100%;
position: fixed;
background: black;
float: left;
}
ul, li {
list-style: none;
margin: 0;
padding: 0;
float: left;
}
a {
padding: 10px 20px 20px;
}
.current a {
background: transparent url('../img/wedge-red.png') center bottom no-repeat;
}
The only way I can think to do it is to add extra divs on either side of the ul and assign the background to them, and then use a transparent png with a cutout as the background of the li a's.
Is there a way to do this without getting really ugly like that, and adding extra divs?

Answer 1

Try CSS pseudo elements!
Add 2 free DOM elements before and after an existing element in the DOM. Ideal in cases when you don't want to add stuff to your markup to satisfy styling needs.
CSS Markup
.item:before {
content:"";
display: inline-block;
width: 20px;
height: 20px;
background-color: silver;
}
.item:after {
content:"";
display: inline-block;
width: 20px;
height: 20px;
background-color: gray;
}
HTML
<div class="item">Content</div>
Check this JSFiddle for a demo.
Make sure you set content: "" and display:block in order to see them.

Answer 2

Here's what I ended up with -- extending the borders and cropping them with overflow: hidden; (a little hacky, but it works and doesn't add elements to the DOM):
.navbar {
width: 100%;
height: 60px;
position: fixed;
overflow: hidden;
}
ul {
border-left: solid black 2000px;
border-right: solid black 2000px;
position: absolute;
top: 0;
left: 50%;
margin-left: -2000px;
}
The above worked nicely for my purposes, and behaves in a responsive environment.
The other answer on this page, using :before and :after pseudo elements didn't work for my purposes. It ended up being too fussy, the pseudo elements wouldn't align properly, and kept wrapping to the next line when the browser window was resized. That solution as suggested works with fixed-width elements, not percentages as was specified in the original question.