bulma (file, components): fix color fo icons: icons have no color specified anymore for a while, and use the color of parent elements. As they are often used in a `<a>` element (to work without javascript), they are often using a link color. This commit change a few icons to use a dark color instead.

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

{% block body %}
<h1>{% trans %}Not Found{% endtrans %}</h1>
<p>{% trans %}Sorry, we can't find the resource you are trying to access.{% endtrans %}</p>
{% endblock body %}