{% load static %}

<li>
    <form method="POST" action="{% url "index" %}">
        {% csrf_token %}
        <input type="hidden" name="index_id" value='{{ item.id }}'>
        <button class="icon-only-button">
            {% if is_index %}
                <img class="icon" src="{% static "inventory/img/star-filled.svg" %}">
            {% else %}
                <img class="icon" src="{% static "inventory/img/star-outline.svg" %}">
            {% endif %}
        </button>
    </form>
</li>