anchor.diff:      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:”
  
positive.code:     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.
  
    h3 Modifications applied for both WAHTWG HTML Standard and W3C HTML 5.1
    ul
      li Normalize white spaces excluding <code>pre</code> eleemnts
      li Sort attributes alphabetically
      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
  
negative.code:   h1= title
  
    h2 Q. What’s this?
    p This site 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. At the time of writing this, The differences include:
    ul
      li <code>hgroup</code>
      li <code>blockquote</code>
      li <code>main</code>
      li <code>a[ping]</code>
      li <code>ruby</code>
      li <code>cite</code>
      li <code>iframe[seamless]</code>
      li Table sorting model
      li <code>input[type="datetime-local"]</code> and <code>input[type="datetime"]</code>
      li Canvas 2D Context
      li Microdata
      li <code>requestAnimationFrame</code>
      li Sever-sent events
      li <code>postMessage</code> and <code>onmessage</code>
      li Web Sockets API
      li Web Workers
      li Web Storage
      li requirements for alternative texts of images
      li <code>showModalDialog</code>
    p I can’t remember those differences. Thus I created this site.
    p This site is not affiliate with WHATWG nor W3C.
  
    h2 Q. Are table of contents (TOCs) displayed in this site same as the specifications?
    p No. This site modifies original TOCs as follows to reduce unnecessary diffs.
  
    h3 Modifications applied for both WAHTWG HTML Standard and W3C HTML 5.1
    ul
  