anchor.diff:      li Replace “Plugin Content Handlers” with “Plugins” in “Common infrastructure”
       li Reorder “Links” in “The elements of HTML”
   
  -  h2 Q. Are HTMLs displayed in this service same as the specifications?
  -  p No. This service reformats HTMLs to reduce unnecessary diffs.
  -  p Though I admit that reformatting creates another clutters of diffs, it is better than do nothing.
  +  h2 Q. Are HTMLs displayed in this site same as the specifications?
  +  p No. This site reformats HTMLs to reduce unnecessary diffs.
   
     h3 Modifications applied for both WAHTWG HTML Standard and W3C HTML 5.1
     ul
  -    li Normalize white spaces excluding <code>pre</code> eleemnts
  +    li Normalize white spaces excluding <code>pre</code>
       li Sort attributes alphabetically
  +    li Remove start and end tags of <code>a</code>, <code>em</code>, <code>strong</code>, <code>small</code>, <code>s</code>, <code>cite</code>, <code>q</code>, <code>dfn</code>, <code>abbr</code>, <code>data</code>, <code>time</code>, <code>code</code>, <code>var</code>, <code>samp</code>, <code>kbd</code>, <code>i</code>, <code>b</code>, <code>u</code>, <code>mark</code>, 
       li Remove <code>data-*</code> attributes
       li Remove <code>id</code> attributes
  -    li Make all <code>href</code> attributes point to “#” (<code>href='#'</code>)
   
     h3 Modifications applied for WHATWG HTML Standard
     ul
  
positive.code:   h1= title
  
    h2 Q. What’s this?
    p This service is an unofficial diff viewer for <a href="https://html.spec.whatwg.org/multipage/">WHATWG HTML Standard</a> and <a href="https://w3c.github.io/html/">W3C HTML 5.1 Editor's Draft</a>.
    p There are number of differences between WHATWG HTML Standard and W3C HTML 5.1 Editor's Draft including Canvas 2D Context, Web Workers, Web Storage, Web Sockets API, Microdata, <code>postMessage</code>, <code>requestAnimationFrame</code>, <code>hgroup</code>, <code>main</code>, <code>a[ping]</code>, ruby model, requirements for alternative texts of images, <code>iframe[seamless]</code>, <code>showModalDialog</code>, and so on. I can’t remember those differences. Thus I create this service.
    p This service is not affiliate with WHATWG nor W3C.
  
    h2 Q. Are table of contents (TOCs) displayed in this service same as the specifications?
    p No. This service modifies original TOCs as follows to reduce unnecessary diffs.
  
    h3 Modifications applied for both WAHTWG HTML Standard and W3C HTML 5.1
    ul
  
negative.code:     li Remove start and end tags of  <code>span</code> used in syntax highlighting
      li Remove start and end tags of <code>span.secno</code> and <code>span.content</code> used in headings
      li Remove <code>a.self-link</code>
      li Remove highlight from <code>class</code> attribute
      li Remove <code>role</code> attribute (ex. <code>role=note</code>)
      li Remove “Allowed ARIA role attribute values:” and “Allowed ARIA state and property attributes:”
  