Wikipedia:COLOUR

Web accessibility is the goal of making web pages easier to navigate and read. While this is primarily intended to assist those with disabilities, it can be helpful to all readers. We aim to adhere to WCAG guidelines 2.0 (a.k.a. ISO/IEC 40500:2012) on which the following suggestions are based. Articles adhering to them are easier to read and edit for everyone.

... and says: .

A standardized structure of articles improves accessibility, because it enables users to expect contents to be in a specific part of the page. For example, a blind user is searching for disambiguation links. If he doesn't find any at the top of the page, he will know that there aren't any and he doesn't have to read the whole page to find that out.

Headings should be descriptive and in a consistent order as defined in the Manual of Style.

Nest headings sequentially, starting with level 2 (==), then level 3 (===) and so on. (Level 1 is the auto-generated page title.) Do not skip parts of the sequence, such as selecting levels for emphasis; this is not the purpose of headings.

[Article lead here]
==Section== [level 2]
===Sub-section=== [3]
==Section== [2]
===Sub-section=== [3]
====Sub-sub-section==== [4]
==Section== [2]

[Article lead here]
====Section?==== [4]
===Section?=== [3]
==Section?== [2]
==Section?== [2]
====Section?==== [4]
===Section?=== [3]

[Article lead here]
[Level-2 section missing here]
===Section?=== [3]
==Section== [2]
[Level-3 sub-section missing here]
====Sub-section?==== [4]
==Section== [2]

Do not make pseudo-headings by abusing semicolon markup (reserved for description lists) and try to avoid using bold markup. Screen readers and other machines can only use correctly formatted headings for navigation. If you want to reduce the size of the table of contents (TOC), use {{}} instead. In cases where {{}} cannot be used because of lower-level headings elsewhere in the article, then using bold for the headings causes the least annoyance for screen reader users.

...
Wikipedia