Keyframes.app | CSS Animation/Keyframe editor | Animation library

I've been trying to develop a CSS keyframes animation for a navigation bar.

You can see in the code snippet how the animation works - the red line is animated when the user clicks an element of the nav bar. The first element of the nav bar is active by default (the red line is under this element). When an element is clicked, the JS takes the properties of the animation element, as well as the properties of the element that was clicked. These properties are incorporated into new keyframes that are inserted into the single keyframes rule.

When the second element is clicked, the animation runs successfully from element 1 --> 2. The animation also runs successfully from element 1 --> 3.

But after the animation plays from element 1 --> 2, it won't play from element 2 --> 3. The animationend event does not trigger (I checked this). As of now, I'm only concerned with the animation going forwards.

After researching, I tried several methods to fix this. Removing and reattaching the animation class does not work, even with a DOM reflow being triggered. Changing the animation-play-state from 'running' to 'paused' does not work either. Other solutions, such as changing the animation-name to 'none' and then back, only generate more problems, like the position of the animation element being reset upon the ending of the animation. I truly do not know how to fix this.

I would prefer to make a flexible keyframes animation, such as this, rather than brute-forcing it. A brute force scenario would include making 6 different keyframes rules, and I want the code to be applicable to any number of elements in the navigation bar. Adding keyframes rules for every addition of an element would require exponentially more code each addition.

Thanks.

~ Code for demo ~