Prevent menu animation transition on page load - html

Question

I'm building a menu with an "indicator" just like this codepen: https://codepen.io/jnowland/pen/XmQGNx
Everything works perfectly except for one little tiny detail: When the link is clicked and that page loads, the indicator animates from the previous child before settling on the link that just became .active. This can't be seen in the linked example, only the hover effect. This is a screen recording of my menu (sorry for the low gif framerate):
You can see how the hover works perfectly but note how the transition jumps from the menu item before after a link is clicked and that page loads. I don't want a transition here. How can I prevent that? My code looks almost exactly the same as the codepen for the parts that control this so please refer to the code in the link.
.Nav-item {
&:last-child {
&:before, &:after {
content: '';
display: block;
position: absolute;
pointer-events: none;
transition: left #{$transition-speed} ease;
}
My initial thought was deleting the transition from this part but it messes up the whole transition so it has to stay.
.Nav-item:nth-child(#{$i}).is-active ~ .Nav-item:last-child:before
{
left:($width*$i)+($width/2)-$width;
.Nav-item:nth-child(#{$i}):hover ~ .Nav-item:last-child:before{
left:($width*$i)+($width/2)-$width !important;
}
Adding the transition inside these two and delete from the first code block doesn't seem to be the right way to go either.

Answer 1

After days of trial and error I accidentally jumped over what I now think is why the menu is persistent and displays this error:
On page load, the tool I work with (MonoSolutions) adds a separate li item first in the list for the swipe menu close button, but it is set to hide for all screen sizes above mobile. This hidden state takes a fraction of a second to load and just before that happens, all nth-child(#) is one step behind. The unwanted transition is seen when the first list item hides.
Note: The code is probably correct, if you'd work outside a stupid WYSIWYG editor.