Make footer stick to the bottom of the page

- Use JavaScript to determine height of `.page_footer` to apply padding to `body` avoiding any content overlap
- Absolute position `.page_footer` to bottom of the page

assets/_scss/_base.scss

@@ -2,6 +2,12 @@
    BASE ELEMENTS
    ========================================================================== */
 
+html {
+  /* sticky footer fix */
+  position: relative;
+  min-height: 100%;
+}
+
 body {
   margin: 0;
   padding: 0;

assets/_scss/_footer.scss

@@ -5,6 +5,13 @@
 .page__footer {
   @include full();
   @include clearfix;
+  /* sticky footer fix start */
+  position: absolute;
+  bottom: 0;
+  width: 100%;
+  clear: both;
+  height: auto;
+  /* sticky footer fix end */
   margin-top: 3em;
   color: mix(#fff, $gray, 25%);
   animation: intro 0.3s both;