fixed html syntax errors in courses.html

templates/courses.html

 {% from 'macros.html' import course_list_item %}
 {% extends "base.html" %}
 {% block content %}
-<div clss="row">
+<div>
 	<div class="col-xs-12" style="padding: 0px;">
 		<ul class="list-inline pull-right">
 			<li>
@@ -51,10 +51,10 @@
 {% endif %}
 
 {% for g in grouped_courses %}
-<div class="row panel-group" id="accordion">
+<div class="row panel-group" id="accordion-{{ g.grouper|tagid }}">
 	<div class="col-xs-12"><div class="panel panel-default">
 		<div class="panel-heading">
-			<a class="accordion-toggle" data-toggle="collapse" data-parent="#accordion" href="#{{g.grouper|tagid}}" style="color: #222;">
+			<a class="accordion-toggle" data-toggle="collapse" data-parent="#accordion-{{ g.grouper|tagid }}" href="#{{g.grouper|tagid}}" style="color: #222;">
 				{% if groupedby == 'semester' %}
 				<h1 class="panel-title">{{g.grouper|semester(long=True)}} ({{g.list|length}} Veranstaltungen)</h1>
 				{% else %}