add go to top arrow (#675)

Author: Arhell

_layouts/bootstrap.html

@@ -317,8 +317,12 @@ <h4 class="mt-8">additional_thanks_to_</h4>
 <!-- Google Tag Manager (noscript) -->
 <noscript><iframe src="https://www.googletagmanager.com/ns.html?id=GTM-KW4XGH4"
 height="0" width="0" style="display:none;visibility:hidden"></iframe></noscript>
-<!-- End Google Tag Manager (noscript) -->    
-    
+<!-- End Google Tag Manager (noscript) -->
+
+<div class="scroll-to-top" id="scroll-to-top" style="display: none">
+    <svg xmlns="http://www.w3.org/2000/svg" shape-rendering="geometricPrecision" text-rendering="geometricPrecision" image-rendering="optimizeQuality" fill-rule="evenodd" clip-rule="evenodd" viewBox="0 0 512 312.36"><path fill-rule="nonzero" d="M0 276.77 253.12 0 512 282.48l-32.65 29.88-226.2-246.83L32.66 306.64z"/></svg>
+</div>
+
 {% include js.html %}
 
 {% include twitter.html %}

_scss/_main.scss

@@ -1765,4 +1765,23 @@ body #footer .links {
     margin-left: 0 !important;
     margin-bottom: 20px;
   }
-}
+}
+
+.scroll-to-top {
+  width: 50px;
+  height: 50px;
+  border-radius: 50%;
+  font-size: 30px;
+  text-align: center;
+  color: #236BFD;
+  background-color: #ffffff;
+  position: fixed;
+  bottom: 50px;
+  right: 50px;
+  cursor: pointer;
+  svg {
+    width: 20px;
+    height: 20px;
+    fill: #236BFD;
+  }
+}

js/scripts.js

@@ -91,6 +91,20 @@ $(document).ready(function () {
             $('#contributors').append('<p style="clear: both">Join us, fork Codeception and submit your pull requests!</p>');
         }
     });
+
+    $('#scroll-to-top').click(function () {
+        $('html, body').animate({scrollTop: 0}, 400);
+        return false;
+    });
+
+    $(window).scroll(function () {
+        var threshold = 300;
+        if ($(window).scrollTop() > threshold) {
+            $('#scroll-to-top').fadeIn('slow');
+        } else {
+            $('#scroll-to-top').fadeOut('slow');
+        }
+    });
 });
 
 // js