Do not display checksums on small devices

ivatar/tools/templates/check.html

@@ -23,6 +23,7 @@
     <p>
       This is what the avatars will look like depending on the hash and protocol you use:<br/>
 
+      <div class="d-none d-lg-block">
         {% if mail_hash %}
           MD5 hash (mail): {{ mail_hash }}<br/>
           SHA256 hash (mail): {{ mail_hash256 }}<br/>
@@ -31,6 +32,7 @@
         {% if openid_hash %}
           SHA256 hash (OpenID): {{ openid_hash }}<br/>
         {% endif %}
+      </div>
     </p>
 
     <ul class="horizontal-list avatar-list centered" style="font-size:smaller;">