bulma (call): add a button for screen sharing: - add a button for screen sharing, only on desktop - split `muted` state to `inactive` and `muted` where `muted` is only about the color - use the `inactive` state with an other color (in `screen-off` class) to indicate when screen is not shared rel 432

{% extends 'error/base.html' %}

{% block body %}
<h1>{% trans %}Unauthorized{% endtrans %}</h1>
<p>{% trans %}Sorry, you are not allowed to access this page.{% endtrans %}</p>
{% endblock body %}