Add a line wrapping css to not overflow on little screens, add mini_racer to dependencies to build

Gemfile

@@ -8,3 +8,4 @@ gem 'redcarpet'
 gem 'middleman-syntax'
 gem 'rake'
 gem 'webrick'
+gem 'mini_racer'

source/stylesheets/site.css.scss

@@ -119,6 +119,7 @@ footer {
   padding-top: 1em;
   padding-bottom: 1em;
   overflow-x: auto;
+  white-space: pre-line;
 }
 
 body > main {