Added back-to-top button

Signed-off-by: Jim Martens <github@2martens.de>

_assets/css/main.css.scss

@@ -10,6 +10,14 @@
   border-bottom: 2px solid $light;
 }
 
+#back-to-top {
+  cursor: pointer;
+  position: fixed;
+  bottom: 20px;
+  right: 20px;
+  display:none;
+}
+
 $navbarHeight: 58px;
 
 .large {

_assets/js/main.js

@@ -11,4 +11,22 @@ $(function() {
     mainMenu.on('hidden.bs.collapse', function (e) {
         $('#submenuNavbar').removeClass('invisible');
     });
+
+    let backToTop = $('#back-to-top');
+    $(window).scroll(function () {
+        if ($(this).scrollTop() > 50) {
+            backToTop.fadeIn();
+        } else {
+            backToTop.fadeOut();
+        }
+    });
+    backToTop.click(function() {
+        backToTop.tooltip('hide');
+        $('body,html').animate({
+            scrollTop: 0
+        }, 800);
+        return false;
+    });
+
+    backToTop.tooltip();
 });

_layouts/default.html

@@ -33,6 +33,11 @@
             </div>
         </div>
     </div>
+    <button id="back-to-top"
+       class="btn btn-primary btn-lg"
+       title="Click to return to the start of the page" data-toggle="tooltip" data-placement="left">
+        <span class="fas fa-chevron-square-up"></span>
+    </button>
 </div>
 {% include footer.html %}
 </body>

pages/about.html

@@ -24,7 +24,8 @@ description: Here you can find meta information about this website.
     </li>
     <li><span class="font-weight-bold">(Almost) no javascript</span>:
         This site uses almost no javascript. Javascript is only used to make the menus responsive, to replace the
-        Font Awesome span elements with svg elements and to load images on demand to make site loading faster.
+        Font Awesome span elements with svg elements, to offer a "back-to-top" button and to load images on demand to
+        make site loading faster.
     </li>
     <li><span class="font-weight-bold">(Almost) no external requests</span>:
         To protect your privacy as good as possible, the amount of external requests is as low as possible. External