Update Bootstrap

views/index.pug

@@ -9,7 +9,7 @@ block head
     }
     body {
       font-family: "Open Sans", -apple-system, BlinkMacSystemFont, "Segoe UI", Roboto, "Helvetica Neue", Arial, sans-serif;
-      margin-bottom: 60px;
+      margin-bottom: 4rem;
     }
     @media (min-width: 1800px) {
       .container {
@@ -31,10 +31,10 @@ block head
     }
     footer {
       width: 100%;
-      height: 35px;
+      height: 2.5rem;
       position: absolute;
       bottom: 0;
-      line-height: 35px;
+      line-height: 2rem;
     }
 block content
   main.container.m-t-3.m-x-6

views/layout.pug

@@ -4,7 +4,7 @@ html(lang='en')
     meta(charset='utf-8')
     meta(name='viewport', content='width=device-width, initial-scale=1, shrink-to-fit=no')
     title #{title}
-    link(rel='stylesheet', href='https://maxcdn.bootstrapcdn.com/bootstrap/4.0.0-alpha.3/css/bootstrap.min.css', integrity='sha384-MIwDKRSSImVFAZCVLtU0LMDdON6KVCrZHyVQQj6e8wIEJkW4tvwqXrbMIya1vriY', crossorigin='anonymous')
+    link(rel='stylesheet', href='https://maxcdn.bootstrapcdn.com/bootstrap/4.0.0-alpha.4/css/bootstrap.min.css', integrity='sha256-SC9pI7daKIBEHzXq0JEtOr9yMl5V7yMMqoowsw8uzNs=', crossorigin='anonymous')
 
     block head