Update image, center it and limit its sizes

aleksis/apps/alsijil/static/css/alsijil/full_register.css

@@ -130,3 +130,14 @@ table.person-info td.person-img img {
 .sheet * {
     page-break-inside: avoid;
 }
+
+img.max-size-600 {
+  max-width: 600px;
+  max-height: 600px;
+}
+
+img.center{
+  position: relative;
+  left: 50%;
+  transform: translateX(-50%);
+}

aleksis/apps/alsijil/templates/alsijil/print/full_register.html

@@ -14,7 +14,9 @@
     <section class="sheet padding-10mm bigprint" id="titlepage">
       <div>
         <h1>{% trans 'Class register' %}</h1>
-        <img src="{% cropped_thumbnail school 'logo_cropping' max_size='600x600' %}" id="school-logo" />
+        {% static "img/aleksis-banner.svg" as aleksis_banner %}
+        <img src="{% firstof request.site.preferences.theme__logo.url aleksis_banner %}"
+             alt="{{ request.site.preferences.general__title }} – Logo" class="max-size-600 center">
         <p id="group-desc">
           {{ group.name }}
         </p>