Add logo image resolution in img tag
{% block body %}
{% block header %}
<header id="header">
- {% block header_title %}<h1><a href="{{ site_url }}"><img src="{{ asset(site_logo) }}" alt="{{ site_title }}" /></a></h1>{% endblock %}
+ {% block header_title %}<h1><a href="{{ site_url }}" title="{{ site_title }}"><img src="{{ asset(site_logo) }}" alt="{{ site_title }}" width="171" height="32" /></a></h1>{% endblock %}
{% block header_nav %}
<nav>
<h2>{% trans %}Navigation{% endtrans %}</h2>