CSS Stepper - LI After overlaying LI Before - css

Question

I'm using some code found at codepen with a Stepper Control. I'm not vey skilled with CSS and I'm having an issue not presented in codepen, so I assume is another CSS class defined in a very long stylesheet that is shared with other team mates. The problem I tried to fix is that the line defined in the class .progressbar li:after remains above the class .progressbar li:before, that defines the circles.
li:after initially came with a z-index: -1 and li:before didn't have the z-index property, but the lines didn't appear, they were hidden behind a div, so I had to modify it and that's what is shown in the snippet. Although this z-index: -1 works in the snippet, is not working where I want to be implemented.
This first image shows the result of the CSS Stepper, taken directly from codepen to my page with z-index:-1
This other image shows the result after trying to adjust the z-index property:
This is the desired output:
Here's the snippet:
.container {
width: 600px;
margin: 100px auto;
z-index: -1;
}
.progressbar li {
list-style-type: none;
width: 25%;
float: left;
font-size: 12px;
position: relative;
text-align: center;
text-transform: uppercase;
color: #666666;
}
.progressbar li:after {
width: 100%;
height: 2px;
content: '';
position: absolute;
background-color: #666666;
top: 15px;
left: -50%;
display: block;
z-index: 1;
}
.progressbar li:before {
width: 30px;
height: 30px;
content: '';
line-height: 30px;
border: 2px solid #666666;
display: block;
text-align: center;
margin: 0 auto 10px auto;
border-radius: 50%;
background-color: white;
z-index: 999999;
}
.progressbar li:first-child:after {
content: none;
}
.progressbar li.active {
color: green;
}
.progressbar li.active:before {
border-color: #55b776;
}
.progressbar li.active + li:after {
background-color: #55b776;
}
<div class="container">
<ul class="progressbar">
<li >aaaaaa</li>
<li class="active">bbbbbbbbbt</li>
<li>cccccccc</li>
<li>ddddddddd</li>
</ul>
</div>
¿Could I get some help to solve this problem, or where could I start looking?
I think it's all said, but please, if I left something, I'll try to complete the post.
Thanks in advance,

Answer 1

You just need to reduce the z-index of .progressbar li:after like this (no other changes required):
.progressbar li:after {
width: 100%;
height: 2px;
content: '';
position: absolute;
background-color: #666666;
top: 15px;
left: -50%;
display: block;
z-index: -999999;
}
You can see it working below:
.container {
width: 600px;
margin: 100px auto;
z-index: -1;
}
.progressbar li {
list-style-type: none;
width: 25%;
float: left;
font-size: 12px;
position: relative;
text-align: center;
text-transform: uppercase;
color: #666666;
}
.progressbar li:after {
width: 100%;
height: 2px;
content: '';
position: absolute;
background-color: #666666;
top: 15px;
left: -50%;
display: block;
z-index: -999999;
}
.progressbar li:before {
width: 30px;
height: 30px;
content: '';
line-height: 30px;
border: 2px solid #666666;
display: block;
text-align: center;
margin: 0 auto 10px auto;
border-radius: 50%;
background-color: white;
z-index: 999999;
}
.progressbar li:first-child:after {
content: none;
}
.progressbar li.active {
color: green;
}
.progressbar li.active:before {
border-color: #55b776;
}
.progressbar li.active+li:after {
background-color: #55b776;
}
<div class="container">
<ul class="progressbar">
<li>aaaaaa</li>
<li class="active">bbbbbbbbbt</li>
<li>cccccccc</li>
<li>ddddddddd</li>
</ul>
</div>

Answer 2

You must give the element a position-value in order to use z-index. Just apply position: relative; to the .progressbar li:before-element:
.container {
width: 600px;
margin: 100px auto;
}
.progressbar li {
list-style-type: none;
width: 25%;
float: left;
font-size: 12px;
position: relative;
text-align: center;
text-transform: uppercase;
color: #666666;
}
.progressbar li:after {
width: 100%;
height: 2px;
content: '';
position: absolute;
background-color: #666666;
top: 15px;
left: -50%;
display: block;
}
.progressbar li:before {
width: 30px;
height: 30px;
content: '';
line-height: 30px;
border: 2px solid #666666;
display: block;
text-align: center;
margin: 0 auto 10px auto;
border-radius: 50%;
background-color: white;
position: relative;
z-index: 1;
}
.progressbar li:first-child:after {
content: none;
}
.progressbar li.active {
color: green;
}
.progressbar li.active:before {
border-color: #55b776;
}
.progressbar li.active+li:after {
background-color: #55b776;
}
<div class="container">
<ul class="progressbar">
<li>aaaaaa</li>
<li class="active">bbbbbbbbbt</li>
<li>cccccccc</li>
<li>ddddddddd</li>
</ul>
</div>