You may want to override your graphsrv html templates in order to customize them, starting with graphsrv 1.1.0 this is now possible.

create a directory that will hold your template overrides

mkdir /path/to/my/templates

create a file called overview.html inside this directory

{% extends 'overview.base.html' %}
{% block head %}
<style type="text/css">
#graphsrv-overview {
  margin-bottom: 50px;
}
</style>
{% endblock %}
{% block footer %}
<div style="text-align: center">
Powered by GraphSrv
</div>
{% endblock %}

update the config to let graphsrv know about the directory

apps:
  graphsrv:
    template_locations:
      - /path/to/my/templates