Better responsiveness, homepage and footer

bin/_template.html

@@ -59,7 +59,8 @@ $body$
 <footer class="bg-light mt-5 py-5">
   <div class="container">
     <div class="row">
-      <div class="col-3">
+
+      <div class="col-6 col-sm-3">
         <a href="$rel-root$">
           <i class="fas fa-home"></i>
           Home
@@ -72,7 +73,8 @@ $body$
           <li><a href="$rel-root$/download">Download GF</a></li>
         </ul>
       </div>
-      <div class="col-3">
+
+      <div class="col-6 col-sm-3">
         <h6 class="text-muted">Learn more</h6>
         <ul class="list-unstyled">
           <li><a href="$rel-root$/gf-book">The GF Book</a></li>
@@ -82,7 +84,8 @@ $body$
           <li><a href="$rel-root$/lib/doc/synopsis/index.html">RGL Library Synopsis</a></li>
         </ul>
       </div>
-      <div class="col-3">
+
+      <div class="col-6 col-sm-3">
         <h6 class="text-muted">Develop</h6>
         <ul class="list-unstyled">
           <li><a href="$rel-root$/doc/gf-developers.html">Developers Guide</a></li>
@@ -92,7 +95,8 @@ $body$
           <li><a href="$rel-root$/doc/gf-editor-modes.html">Text Editor Support</a></li>
         </ul>
       </div>
-      <div class="col-3">
+
+      <div class="col-6 col-sm-3">
         <h6 class="text-muted">Contribute</i>
         </h6>
         <ul class="list-unstyled">
@@ -101,7 +105,6 @@ $body$
           <li><a href="$rel-root$/doc/gf-people.html">Authors</a></li>
           <li><a href="http://school.grammaticalframework.org/2018/">Summer School</a></li>
         </ul>
-
         <h6 class="text-muted">
           Repositories
           <i class="fab fa-github ml-1"></i>