Added a margin and a couple styles

Added a background, rather than an outline, which should reduce
clutter on the screen.

app/assets/stylesheets/sections/events.scss

@@ -184,6 +184,12 @@
   }
 }
 
-.event_filter li a {
-  padding: 5px 10px;
+.event_filter {
+  
+  li a {
+    padding: 5px 10px;
+    background: rgba(0,0,0,0.045);
+    margin-left: 4px;
+  }
+
 }

app/helpers/events_helper.rb

@@ -30,7 +30,7 @@ module EventsHelper
              end
 
     content_tag :li, class: "filter_icon #{active}" do
-      link_to request.path, class: 'btn has_tooltip event_filter_link', id: "#{key}_event_filter", 'data-original-title' => tooltip do
+      link_to request.path, class: 'has_tooltip event_filter_link', id: "#{key}_event_filter", 'data-original-title' => tooltip do
         icon(icon_for_event[key]) + content_tag(:span, ' ' + tooltip)
       end
     end