anchor.diff:  
   .s-rule.do
     :marked
  -    **Do** create an Angular module at the root of the application.
  -
  -.s-why
  -  :marked
  -    **Why?** Every app requires at least one Angular module.
  +    **Do** create an Angular module in the app's root folder (e.g., in `/app`).
  +
  +.s-why
  +  :marked
  +    **Why?** Every app requires at least one root Angular module.
   
   .s-rule.consider
     :marked
  
positive.code: 
  a(id='file-tree')
  :marked
    Folder and File Structure
  
  .filetree
    .file src
    .children
      .file app
      .children
  
negative.code:         .file villains.module.ts
          .file villains-routing.module.ts
        .file app.component.ts|html|css|spec.ts
        .file app.module.ts
        .file app-routing.module.ts
      .file main.ts
      .file index.html
      .file ...
  