feat: push footer to window bottom for short pages

Remove 100% height for .parallax as conflicts with new page grid CSS and Leaflet map interactions.

wowchemy/assets/scss/wowchemy/_widgets.scss

@@ -75,7 +75,6 @@
 
 /* Create a parallax-like scrolling effect. */
 .parallax {
-  height: 100%;
   background-attachment: fixed;
 }