<body> <h1>I'm a Level 1 Heading.</h1> <section> <h1>I'm a Level 1. Supposed to act as a Level 2.</h1> <section> <h1>I'm a Level 1. Supposed to act as a Level 3.</h1> <section> <h1>I'm a Level 1. Supposed to act as a Level 4.</h1> <section> <h1>I'm a Level 1. Supposed to act as a Level 5.</h1> </section> </section> </section> </section></body>
<body> <h4>Apples</h4> <p>Apples are fruit.</p> <section> <h2>Taste</h2> <p>They taste lovely.</p> <h6>Sweet</h6> <p>Red apples are sweeter than green ones.</p> <h1>Color</h1> <p>Apples come in various colors.</p> </section></body>
<body> <h1>Apples</h1> <p>Apples are fruit.</p> <section> <h2>Taste</h2> <p>They taste lovely.</p> <section> <h3>Sweet</h3> <p>Red apples are sweeter than green ones.</p> </section> </section> <section> <h2>Color</h2> <p>Apples come in various colors.</p> </section></body>
as-is
Sectioning Root
Sectioning Content Element
æé»ã®ã»ã¯ã·ã§ã³
æé»ã®ã»ã¯ã·ã§ã³
to-be
Sectioning Content Element
æé»ã®ã»ã¯ã·ã§ã³
æé»ã®ã»ã¯ã·ã§ã³
<body> <h1>I'm a Level 1 Heading.</h1> <section> <h1>I'm a Level 1. Supposed to act as a Level 2.</h1> <section> <h1>I'm a Level 1. Supposed to act as a Level 3.</h1> <section> <h1>I'm a Level 1. Supposed to act as a Level 4.</h1> <section> <h1>I'm a Level 1. Supposed to act as a Level 5.</h1> </section> </section> </section> </section></body>
<body> <h1>I'm a Level 1 Heading.</h1> <section> <h2>I'm a Level 1. Supposed to act as a Level 2.</h2> <section> <h3>I'm a Level 1. Supposed to act as a Level 3.</h3> <section> <h4>I'm a Level 1. Supposed to act as a Level 4.</h4> <section> <h5>I'm a Level 1. Supposed to act as a Level 5.</h5> </section> </section> </section> </section></body>
Sections may contain headings of any rank, but authors are strongly encouraged to either use only h1 elements, or to use elements of the appropriate rank for the sectionâs nesting level.
â Warning! There are currently no known native implementations of the outline algorithm in graphical browsers or assistive technology user agents, although the algorithm is implemented in other software such as conformance checkers and browser extensions. Therefore the outline algorithm cannot be relied upon to convey document structure to users. Authors should use heading rank (h1-h6) to convey document structure.
HTML 5.2: 4.3. Sections https://html.spec.whatwg.org/multipage/sections.html#creating-an-outline
ãOutline Algorithm ã¯äžåã«å®è£ ãããªãããStructural ãªã³ã³ãã³ãã¯çŸä»£ã® Web ã«ãšã£ãŠæ¬ ãããªãããªãã°ãå¥ã®æ段㧠Structural ãªæå³ã HTML ã«æãããããšã¯ã§ããªããïŒã
<h>
Heading Level Concept
Over 34 yearâs old, yet brand-new: <h>
<h> ãšããã¢ã€ãã£ã¢èªäœã¯ãå®ã¯ Tim Berners-Lee ã Web ãå§ããã°ããã® 1991 幎ããååšãã
I would in fact prefer, instead of <H1>, <H2> etc for headings [those come from the AAP DTD] to have a nestable <SECTION>..</SECTION> element, and a generic <H>..</H> which at any level within the sections would produce the required level of heading. www-talk from September to October 1991: Re: status. Re: X11 BROWSER for WWW
<h>ïŒ
æ¢ã«å®è£ æžã¿ã® Sectioning Content Elements ãšçµã¿åãããOutline Algorithm ã«ãã£ãŠãSection ã®ã³ã³ããã¹ãã«å¿ããèŠåºãã¬ãã«ãèªåçã«æ±ºå®ããããã«ææ¡ãããèŠçŽ
<section> <h>I can be any Level depending on the section context!</h> <p>paragraph</p></section>
ãOutline Algorithm 㧠Outline ãçæããããšãã§ã¯ãªããSectioning Content å ã®èŠåºãã¬ãã«ã調æŽããããšãã«çŠç¹ãåœãŠã Anne van Kesteren ã®ææ¡
// https://github.com/annevk/html-heading-level-polyfill/blob/main/polyfill.jsfunction determineLevel(el) { let level = 1; // Arguably the parentNode being null check can be removed as it will never be null when this and // the function below are run on a document, as is the case. // // This is "sectioning content" and "sectioning roots" while (el.parentNode && (el = el.parentNode.closest("article,aside,nav,section,blockquote,details,dialog,fieldset,figure,td"))) { level += 1; } return level;}
Anne ã®äœã£ã Heading Levels ã® Polyfill
ãã® Polyfill ã®ã¢ã«ãŽãªãºã ã¯éåžžã«ã·ã³ãã«ã§ã
In the following CSS block, x is shorthand for the following selector: :is(article, aside, nav, section)@namespace "http://www.w3.org/1999/xhtml";x h1 { margin-block: 0.83em; font-size: 1.50em; }x x h1 { margin-block: 1.00em; font-size: 1.17em; }x x x h1 { margin-block: 1.33em; font-size: 1.00em; }x x x x h1 { margin-block: 1.67em; font-size: 0.83em; }x x x x x h1 { margin-block: 2.33em; font-size: 0.67em; }
HTMLã«ãããŠãèŠèŠç㪠Semanticsãããæ§é çãªæå³ãããåªå ãããçµæãå€ãã®æ··ä¹±ãçãããèŠèŠãæ£ããããã«èŠããã°æ§é ãã¡ãã£ã¯ãã£ã§ãæ°ã«ããªããšããç¶æ³ãçã¿åºããŠããŸã£ã