CSS Animation on Menu item is not working when hovering - html

Question

I wanted to add a hover effect to my menu item, so when hovered, an line would be transitioning under it, and the line would expand from the middle out. I have included links two 2 gifs (one showing the intended animation and one showing the current result.
The structure is as follows
#main-nav .navbar-nav li:hover .top_level::after {
opacity: 1;
-webkit-transform: scaleX(1);
transform: scaleX(1);
width: calc(100%);
}
#main-nav .navbar-nav li:hover .top_level::after {
content: "";
background-color: #000;
display: block;
height: 2px;
opacity: 0;
bottom: 28px;
position: absolute;
right: 0;
left: 0;
margin: 0 auto;
-webkit-transform: scaleX(0);
transform: scaleX(0);
-webkit-transition: opacity 0.3s ease 0s, -webkit-transform 0.3s ease 0s;
transition: opacity 0.3s ease 0s, -webkit-transform 0.3s ease 0s;
transition: opacity 0.3s ease 0s, transform 0.3s ease 0s;
transition: opacity 0.3s ease 0s, transform 0.3s ease 0s, -webkit-transform 0.3s ease 0s !important;
width: calc(100%);
}
.navbar-nav li .top_level {
font-family: "Brandon Bold",Helvetica,Arial,sans-serif !important;
text-transform: uppercase;
font-size: 11px !important;
letter-spacing: 1.25px !important;
line-height: 28px;
color: #000;
padding: 25px 0px !important;
display: inline-block;
border-bottom: 2px solid transparent;
transition: border-color .25s ease-in-out;
position: relative;
text-decoration: none;
}
ul#main-nav {
text-align: left;
}
ul#main-nav {
padding-left: 20px;
}
ul#main-nav {
list-style: none;
text-align: left;
margin-bottom: 0;
width: 100%;
}
ul#main-nav li {
display: inline-block;
vertical-align: middle;
}
.navbar-nav li {
padding: 0 25px;
}
<ul id="main-nav">
<div class="navbar-nav">
<li><a class="top_level" href="/">Cuffs</a></li>
</div>
</ul>
The current result:
https://imgur.com/a/A8nmeQd
The intended result:
https://imgur.com/a/d9JyyhM
How can it be, that the animation doesn't load?
Thank you. :)

Answer 1

The problem is only the second selector (the initial status), which should be #main-nav .navbar-nav li .top_level::after instead of #main-nav .navbar-nav li:hover .top_level::after
Remove the :hover in there and it will work, as it does in the snippet below.
#main-nav .navbar-nav li:hover .top_level::after {
opacity: 1;
-webkit-transform: scaleX(1);
transform: scaleX(1);
width: calc(100%);
}
#main-nav .navbar-nav li .top_level::after {
content: "";
background-color: #000;
display: block;
height: 2px;
opacity: 0;
bottom: 28px;
position: absolute;
right: 0;
left: 0;
margin: 0 auto;
-webkit-transform: scaleX(0);
transform: scaleX(0);
-webkit-transition: opacity 0.3s ease 0s, -webkit-transform 0.3s ease 0s;
transition: opacity 0.3s ease 0s, -webkit-transform 0.3s ease 0s;
transition: opacity 0.3s ease 0s, transform 0.3s ease 0s;
transition: opacity 0.3s ease 0s, transform 0.3s ease 0s, -webkit-transform 0.3s ease 0s !important;
width: calc(100%);
}
.navbar-nav li .top_level {
font-family: "Brandon Bold",Helvetica,Arial,sans-serif !important;
text-transform: uppercase;
font-size: 11px !important;
letter-spacing: 1.25px !important;
line-height: 28px;
color: #000;
padding: 25px 0px !important;
display: inline-block;
border-bottom: 2px solid transparent;
transition: border-color .25s ease-in-out;
position: relative;
text-decoration: none;
}
ul#main-nav {
text-align: left;
}
ul#main-nav {
padding-left: 20px;
}
ul#main-nav {
list-style: none;
text-align: left;
margin-bottom: 0;
width: 100%;
}
ul#main-nav li {
display: inline-block;
vertical-align: middle;
}
.navbar-nav li {
padding: 0 25px;
}
<ul id="main-nav">
<div class="navbar-nav">
<li><a class="top_level" href="/">Cuffs</a></li>
</div>
</ul>