Django Grappelli Admin: sidebar changelist with filter highlight

admin.py

from django.contrib import admin

class AdminChangelistMixin(admin.ModelAdmin):
    change_list_template = "grappelli-overrides/change_list_filter_sidebar.html"
    change_list_filter_template = "grappelli-overrides/filter.html"
    pass

change_list_filter_sidebar.html

{# templates/grappelli-overrides/change_list_filter_sidebar.html #}
{% extends "admin/change_list_filter_sidebar.html" %}

{% load i18n %}
{% load staticfiles %}
{% load admin_list %}
{% load admin_urls %}
{% load grp_tags %}

<!-- FILTERS -->
{% block filters %}
    
    <style type="text/css" media="screen">
        #grp-filters.closed .grp-module {
            display:none;
        }
        /* HTML & Styles uses font Awesome carets for closing */
        #grp-filters .fa { display:none; padding:0 0.5em; }
        #grp-filters .fa-caret-down { display:inline; }
        #grp-filters.closed .fa-caret-down { display:none; }
        #grp-filters.closed .fa-caret-right { display:inline; }
        #grp-filters.closed h2 {
            border-bottom:none;
        }
        #grp-filters h2 a {
            color:inherit;
            cursor:pointer;
        }
        #grp-filters.grp-module.selected,
        #grp-filters.grp-module.selected h2 {
            border-color: #36b0d9;
        }
        #grp-filters.grp-module.selected h2 {
            color :#fff;
            background: url('data:image/svg+x…pZHRoPSIxMDAlIiBoZWlnaHQ9IjEwMCUiIGZpbGw9InVybCgjZ3JhZCkiIC8+PC9zdmc+IA==');
            background: -webkit-gradient(linear, 50% 0%, 50% 100%, color-stop(0%, #36b0d9),color-stop(100%, #309bbf));
            background: -moz-linear-gradient(#36b0d9,#309bbf);
            background: -webkit-linear-gradient(#36b0d9,#309bbf);
            background: linear-gradient(#36b0d9,#309bbf);
            text-shadow: none;
            position: relative;
        }
        #grp-filters.grp-module h2 .reset {
            color: #fff;
            visibility: hidden;
            position: absolute;
            right: 0;
            padding: 0 10px;
        }
        #grp-filters.grp-module h2 .reset:hover {
            text-decoration:underline;
        }
            #grp-filters.grp-module.selected h2 .reset {
                visibility: visible;
            }
    </style>
    
    <div id="grp-filters" class="grp-module grp-filter {% if request.COOKIES.grappelli_filter_hide == "true" %}closed{% endif %}">
        <h2><a class="toggler">{% trans 'Filter' %}<i class="fa fa-caret-down"></i><i class="fa fa-caret-right"></i></a> <a href="?" class="reset">reset</a></h2>
        {% for spec in cl.filter_specs %}{% admin_list_filter cl spec %}{% endfor %}
    </div>
    <script type="text/javascript">
        (function($) {
            
            // Remember closed filter (jquery.cookie.js required)
            $("#grp-filters h2 .toggler").on("click",function(e){
                $("#grp-filters").toggleClass("closed");
                $.cookie('grappelli_filter_hide',$("#grp-filters").hasClass("closed"),{path:'/'});
                e.preventDefault();
                return false;
            });
            
            // Highlight filter box and each filter separately
            {% for key,value in request.GET.items %}{% spaceless %}
                {% for spec in cl.filter_specs %}{% spaceless %}
                    {% if key == spec.lookup_kwarg and value %}
                        $("#grp-filters").addClass("selected");
                        $("#grp-filters .filter-{{ spec.lookup_kwarg }}").addClass("selected");
                    {% endif %}
                    {% if key == spec.lookup_kwarg_isnull and value %}
                        $("#grp-filters").addClass("selected");
                        $("#grp-filters .filter-{{ spec.lookup_kwarg_isnull }}").addClass("selected");
                    {% endif %}
                 {% endspaceless %}{% endfor %}
             {% endspaceless %}{% endfor %}
           
        })(grp.jQuery);
    </script>
{% endblock %}

filter.html

{# templates/grappelli-overrides/filter.html #}
{% load i18n %}
<div class="grp-module filter-{{ spec.lookup_kwarg }} filter-{{ spec.lookup_kwarg_isnull }}">
    <div class="grp-row">
        <label>{% blocktrans with title|capfirst as filter_title %}{{ filter_title }}{% endblocktrans %}</label>
        <select class="grp-filter-choice">
            {% for choice in choices %}<option value="{{ choice.query_string|iriencode }}"{% if choice.selected %} selected='selected'{% endif %}>{{ choice.display }}</option>{% endfor %}
        </select>
    </div>
</div>