Elements not overlapping with z-index - html

Question

In my navigation I have a protruding red box. I want that red box to overlap all Divs bellow it. I set a margin for it so it would space it out among the other elements I put in the black box. The problem is that it's margin is also effecting the layout of separate elements' children bellow it. When I add a negative margin to the child elements of the section bellow it does overlap but I want the red box to be on-top. I use z-index and it doesn't seem to work.
Here's my example on Jsfiddle:
http://jsfiddle.net/1qsuvhnd/29/
HTML
<nav>
<div id="ribbon"></div>
</nav>
<div id="context">
<div class="link"></div>
</div>
CSS
#context {
width: auto;
padding: 20px;
height: 300px;
background-color: blue;
z-index: 1;
}
#context .link {
float: Left;
height: 260px;
width: 300px;
margin-left: -140px;
background-color: White;
z-index:1 !important;
}
nav {
width: auto;
height: 65px;
background-color: black;
z-index:99 !important;
clear:both;
}
nav #ribbon {
float: left;
margin: 0px 50px;
Width: 65px;
height: 130px;
background-color: red;
z-index= 99;
}

Answer 1

To use z-index, you need to specify a position (like absolute, fixed, or relative).
And the last line written is wrong:
z-index = 99;
The correct way to write it is:
z-index: 99;

Answer 2

How about: http://jsfiddle.net/1qsuvhnd/30/
change the ribbon to position: absolute; and fix the z-index = typo :D
Now you don't need that margin hack!!
nav #ribbon {
float: left;
margin: 0px 50px;
Width: 65px;
height: 130px;
background-color: red;
z-index: 99; /* take that equal out and make it a colon */
position: absolute; /* position: absolute to the rescue!!!! */
}

Answer 3

You need to specify a position CSS rule for the nav div for the z-index to work correctly, like this:
nav #ribbon {
float: left;
margin: 0px 50px;
Width: 65px;
height: 130px;
background-color: red;
z-index:99;
position: relative;
}
Here is the new jsFiddle link:
http://jsfiddle.net/1qsuvhnd/54/