Cleaned ids and classes

(cherry picked from commit 2b153ed074811e735aaa58d57a3fcdf7838e17f5)

_sass/layout.scss

@@ -37,7 +37,7 @@
   }
 }
 
-.main-content-wrap {
+.main-wrap {
   @include mq(md) {
     position: absolute;
     top: 0;
@@ -48,9 +48,13 @@
     overflow-x: hidden;
     overflow-y: scroll;
   }
+
+  &:focus {
+    outline: none;
+  }
 }
 
-.main-content {
+.main {
   @include mq(md) {
     position: relative;
     max-width: $content-width;
@@ -62,11 +66,7 @@
   }
 }
 
-.js-main-content:focus {
-  outline: none;
-}
-
-.page {
+.main-content-wrap {
   @include container;
   padding-top: $gutter-spacing-sm;
   padding-bottom: $gutter-spacing-sm;
@@ -77,7 +77,7 @@
   }
 }
 
-.page-header {
+.main-header {
   @include container;
   display: none;
   padding-top: $gutter-spacing-sm;
@@ -101,7 +101,7 @@
   }
 }
 
-.navigation,
+.site-nav,
 .site-header,
 .site-footer {
 
@@ -112,7 +112,7 @@
   }
 }
 
-.navigation {
+.site-nav {
   @include container;
 
   @include mq(md) {