added body padding to avoid footer overlap

Author: yimingzhaomath

_sass/_base.scss

@@ -10,6 +10,7 @@ html {
 body {
   margin: 0;
   padding: 0;
+  padding-bottom: 5em;
   color: $text-color;
   font-family: $global-font-family;
   line-height: 1.5;