high z-index in low z-index - special navigation bar - html

Question

I'm try to do a special navigation-bar.
I will show it in pictures:
this on scrollbar on top
and this on scrollbar down:
So I tried to do header with position: fixed and z-index: 1.
inside nav with z-index high(1000) and
the right block with z-index high(1000)
and the content have z-index: 2 and position: relative.
and it didn't worked :/
**and important thing is that I need the upload div will be in the header
and will be higher (in z-index) from content
I will try to show you in code:
header {
display: block;
position: fixed;
width: 100%;
top: 0;
right: 0;
left: 0;
z-index: 1;
background-color: blue;
}
nav {
width: 100%;
height: 40px;
background-color: green;
z-index: 1000;
}
#upload {
background-color: green;
height: 40px;
width: 40px;
float: right;
margin-right: 0;
z-index: 1000;
}
#content {
position: realative;
display: block;
border: 2px solid #000;
margin-left: auto;
margin-right: auto;
height: 200px;
width: 80%;
background-color: #cacaca;
z-index: 2;
}
<header>
<nav></nav>
<div id="upload">
</div>
</header>
<div id="content">
</div>
thank you,and I'm sorry about my english !!

Answer 1

you will need to move the nav out of the header for the #content z-index to work and need to align nav with fixed positioning or by giving margin
header {
display: block;
position: fixed;
width: 100%;
top: 0;
right: 0;
left: 0;
height: 80px;
background-color: blue;
z-index: 1;
}
nav {
width: 100%;
height: 40px;
z-index: 3;
background-color: green;
position: fixed;
top: 0;
right: 0;
left: 0;
}
#upload {
background-color: green;
height: 40px;
width: 40px;
float: right;
margin-right: 0;
margin-top: 40px;
}
#content {
position: relative;
display: block;
border: 2px solid #000;
margin-left: auto;
margin-right: auto;
height: 200px;
width: 80%;
background-color: #cacaca;
z-index: 2;
}
<header></header>
<nav>
<div id="upload"></div>
</nav>
<div id="content"></div>