Loading standard images via HTTPS

_includes/carpentries.html

 <div class="row">
   <div class="col-md-2" align="center">
-    <a href="{{ site.swc_site }}"><img src="{{ site.github.url }}/assets/img/swc-icon-blue.svg" alt="Software Carpentry logo" /></a>
+    <a href="{{ site.swc_site }}"><img src="{{ site.github.url | replace_first: 'http:', 'https:' }}/assets/img/swc-icon-blue.svg" alt="Software Carpentry logo" /></a>
   </div>
   <div class="col-md-8">
     Since 1998,
@@ -14,7 +14,7 @@
 <br/>
 <div class="row">
   <div class="col-md-2" align="center">
-    <a href="{{ site.dc_site }}"><img src="{{ site.github.url }}/assets/img/dc-icon-black.svg" alt="Data Carpentry logo" /></a>
+    <a href="{{ site.dc_site }}"><img src="{{ site.github.url | replace_first: 'http:', 'https:' }}/assets/img/dc-icon-black.svg" alt="Data Carpentry logo" /></a>
   </div>
   <div class="col-md-8">
     <a href="{{ site.dc_site }}">Data Carpentry</a> develops and teaches workshops on the fundamental data skills needed to conduct research.

_includes/navbar.html

@@ -11,19 +11,19 @@
       {% comment %} Select what logo to display. {% endcomment %}
       {% if page.carpentry == "swc" %}
       <a href="{{ site.swc_site }}" class="pull-left">
-        <img class="navbar-logo" src="{{ site.github.url }}/assets/img/swc-icon-blue.svg" alt="Software Carpentry logo" />
+        <img class="navbar-logo" src="{{ site.github.url | replace_first: 'http:', 'https:' }}/assets/img/swc-icon-blue.svg" alt="Software Carpentry logo" />
       </a>
       {% elsif page.carpentry == "dc" %}
       <a href="{{ site.dc_site }}" class="pull-left">
-        <img class="navbar-logo" src="{{ site.github.url }}/assets/img/dc-icon-black.svg" alt="Data Carpentry logo" />
+        <img class="navbar-logo" src="{{ site.github.url | replace_first: 'http:', 'https:' }}/assets/img/dc-icon-black.svg" alt="Data Carpentry logo" />
       </a>
       {% elsif site.carpentry == "swc" %}
       <a href="{{ site.swc_site }}" class="pull-left">
-        <img class="navbar-logo" src="{{ site.github.url }}/assets/img/swc-icon-blue.svg" alt="Software Carpentry logo" />
+        <img class="navbar-logo" src="{{ site.github.url | replace_first: 'http:', 'https:' }}/assets/img/swc-icon-blue.svg" alt="Software Carpentry logo" />
       </a>
       {% elsif site.carpentry == "dc" %}
       <a href="{{ site.dc_site }}" class="pull-left">
-        <img class="navbar-logo" src="{{ site.github.url }}/assets/img/dc-icon-black.svg" alt="Data Carpentry logo" />
+        <img class="navbar-logo" src="{{ site.github.url | replace_first: 'http:', 'https:' }}/assets/img/dc-icon-black.svg" alt="Data Carpentry logo" />
       </a>
       {% endif %}