Blog Category underline active link in filter

You can use this code to Website Tools > Code Injection > Footer

<script src="https://ajax.googleapis.com/ajax/libs/jquery/3.7.1/jquery.min.js"></script>
<script>
  $(document).ready(function() {
    const url = window.location.href;

    if (url.includes('/tag/ALLE')) {
        $('body').addClass('alle');
    } else if (url.includes('/Private+Living')) {
        $('body').addClass('private-living');
    } else if (url.includes('/tag/Real+Estate')) {
        $('body').addClass('real-estate');
    }
});
</script>
<style>
  body.real-estate li.archive-group a[href*="/tag/Real+Estate"] {
    border-bottom: 1px solid #000;
}
  body.private-living li.archive-group a[href*="/tag/Private+Living"] {
    border-bottom: 1px solid #000;
}
  body.alle li.archive-group a[href*="/tag/ALLE"] {
    border-bottom: 1px solid #000;
}
</style>

In the future, if you want to use Filter Links on Portfolio Page, you can also use this solution, instead of creating blog page