Adding a CSS Pseudo Elements to center of a grid only - css

Question

.parnet{
max-width: 600px;
margin: 0 auto;
background: #f4f4f5;
}
.wrapper {
display: grid;
grid-template-columns: repeat(3, 1fr);
}
.cell {
position: relative;
}
.inner {
width: 80px;
height: 80px;
padding: 40px;
text-align: left;
}
.wrapper .cell:nth-child(2n):before{
content: "";
position: absolute;
left: 0;
top: 50%;
transform: translateY(-50%);
height: 60%;
width: 1px;
background-color:red;
}
<div class="parnet">
<div class="wrapper">
<div class="cell">
<div class="inner">1</div>
</div>
<div class="cell">
<div class="inner">2</div>
</div>
<div class="cell">
<div class="inner">3</div>
</div>
<div class="cell">
<div class="inner">4</div>
</div>
<div class="cell">
<div class="inner">5</div>
</div>
<div class="cell">
<div class="inner">6</div>
</div>
</div>
</div>
I have a grid that I'm trying to add a :before Pseudo Element to create a divider line between each grid cell. I only want the divider lines to show in the center cells and not the outside left and right.
I'm able to achieve this using border-right and then using nth-child(3n) to remove borders. But having trouble trying to do the same using a Pseudo Element
.parent {
background: white;
max-width: 600px;
margin: 0 auto;
.wrapper {
display: grid;
grid-template-columns: repeat(3, 1fr);
.cell {
position: relative;
&:before {
content: "";
position: absolute;
left: 0;
top: 50%;
transform: translateY(-50%);
height: 60%;
width: 1px;
background-color:red;
}
&:nth-child(3n):before {
width: 0;
}
.inner {
max-width: 320px;
width: 320px;
height: 200px;
padding: 57px 43px 40px;
text-align: left;
}
}
}
}

Answer 1

.parnet{
max-width: 600px;
margin: 0 auto;
background: #f4f4f5;
}
.wrapper {
display: grid;
grid-template-columns: repeat(3, 1fr);
}
.cell {
position: relative;
}
.inner {
width: 80px;
height: 80px;
padding: 40px;
text-align: left;
}
.wrapper .cell:before{
content: "";
position: absolute;
right: 0;
top: 50%;
transform: translateY(-50%);
height: 60%;
width: 1px;
background-color:red;
}
.wrapper .cell:nth-child(3n):before {
width: 0;
}
<div class="parnet">
<div class="wrapper">
<div class="cell">
<div class="inner">1</div>
</div>
<div class="cell">
<div class="inner">2</div>
</div>
<div class="cell">
<div class="inner">3</div>
</div>
<div class="cell">
<div class="inner">4</div>
</div>
<div class="cell">
<div class="inner">5</div>
</div>
<div class="cell">
<div class="inner">6</div>
</div>
</div>
</div>
So the clue was to set right: 0; on the cell instead of left:0;
Then uses
.wrapper .cell:nth-child(3n):before {
width: 0;
}
Thanks Keith i'm going to score your answer for giving me that great clue.

Answer 2

This is my answer. I'm using the .cell:nth-child(3n):before for the horizontal lines. I hope this is what you need.
.parent {
background: white;
max-width: 600px;
margin: 0 auto;
font-size:2em;
}
.parent .wrapper {
display: grid;
grid-template-columns: repeat(3, 1fr);
}
.parent .wrapper .cell {
position: relative;
}
.parent .wrapper .cell:before {
content: "";
position: absolute;
right: 50%;
top:.2em;
height: 60%;
width: 1px;
background-color: red;
}
.parent .wrapper .cell:nth-child(3n):before {
width: 300%;
height:1px;
top:100%
}
<div class="parent">
<div class="wrapper">
<div class="cell">1</div>
<div class="cell">2</div>
<div class="cell">3</div>
<div class="cell">4</div>
<div class="cell">5</div>
<div class="cell">6</div>
<div class="cell">7</div>
<div class="cell">8</div>
<div class="cell">9</div>
</div>
</div>