feat(aio): layout max width and design cleanup

- Content container now has a max width and made the body background the same offwhite color so the cut-off is not visible
- Sidenav will always remain at the left of the page
- Added a max width to the api banner of filter search inputs
- Left aligned content container so it is flush with sidenav
- Changed API filter width to match size of filter results

aio/src/app/embedded/api/api-list.component.html

@@ -1,4 +1,4 @@
-<div class="l-flex-wrap banner is-plain api-filter">
+<div class="l-flex-wrap banner is-plain l-content-small api-filter">
 
   <div class="form-select-menu">
     <button class="form-select-button has-symbol" (click)="toggleTypeMenu()">