Fix menu display in mobile version.

_includes/header.html

@@ -6,7 +6,7 @@
         <a class="site-title" href="{{ site.baseurl }}/">{{ site.title }}</a>
 
         <nav class="site-nav">
-          <a href="#" class="menu-icon">
+          <a href="#" class="menu-icon" id="menu-icon">
             <svg viewBox="0 0 18 15">
               <path fill="#424242" d="M18,1.484c0,0.82-0.665,1.484-1.484,1.484H1.484C0.665,2.969,0,2.304,0,1.484l0,0C0,0.665,0.665,0,1.484,0 h15.031C17.335,0,18,0.665,18,1.484L18,1.484z"/>
               <path fill="#424242" d="M18,7.516C18,8.335,17.335,9,16.516,9H1.484C0.665,9,0,8.335,0,7.516l0,0c0-0.82,0.665-1.484,1.484-1.484 h15.031C17.335,6.031,18,6.696,18,7.516L18,7.516z"/>
@@ -14,7 +14,7 @@
             </svg>
           </a>
 
-          <div class="trigger">
+          <div class="trigger" id="div-menu-items-wrapper">
             {% for page in site.pages %}
               {% if page.title %}
               <a class="page-link" href="{{ page.url | prepend: site.baseurl }}">{{ page.title }}</a>
@@ -27,3 +27,19 @@
   </div>
 
 </header>
+<script type="text/javascript">
+    function toggleMenu()
+    {
+        var el = document.getElementById("menu-icon");
+        if (el.style.display != "none")
+        {
+            el = document.getElementById("div-menu-items-wrapper");
+            el.style.display = (el.style.display != "block") ? "block" : "none";
+        }
+    }
+
+    window.onload = function()
+    {
+        document.getElementById("menu-icon").addEventListener('click' , toggleMenu);
+    }
+</script>