Contact | Maersk

马士基 | 综合集装箱物流和供应链服务

Маерск | Интегрированная Контейнерная Логистика и Услуги Цепочки Поставок

Maersk Türkiye | Entegre Konteyner Lojistiği

Maersk | Servicios Integrados de Logística de Contenedores & Cadena de Suministro

Maersk | Servizi di Logistica Integrata dei Container & di Supply Chain

馬士基 | 綜合性貨櫃物流與供應鏈服務

Maersk | Logistique de Conteneurs Intégrée & Services de Chaîne d’Approvisionnement

Maersk | 통합 컨테이너 물류 및 공급망 서비스

Maersk | Logística Integrada de Contêineres e Serviços de Cadeia de Suprimento

All controls on the page - including links, buttons, and fields - should clearly 
indicate when they have been selected by the keyboard.

This is a stricter version of [WCAG 2.4.7](https://www.w3.org/WAI/WCAG21/Understanding/focus-visible.html),
which requires that the focus indicator is visible, but doesn't specify how clearly
it should be visible.

You can confirm this yourself by loading a webpage and using the Tab key to navigate 
through it. Anything you can select should clearly alter its appearance when selected. 
For example, a text field might change color, or have a distinctive border applied. 

## The requirements

The [official requirements](https://w3c.github.io/wcag/understanding/focus-appearance.html) are 
complicated. A simplified version is:

* Surround the control with a solid outline
* The outline must have at least 3:1 contrast with its background
* The outline must have at least 3:1 contrast with its surroundings, or be at least 2px thick

The actual requirements allow for more variation, but generally require that you 
calculate the perimeter and/or area of the focus area, which can be very difficult.

## How to fix

Links and form controls should use a focus selector which contrasts with their
unfocused state, as well as any surroundings of the focus state. 

In practice, the easiest way to accomplish this is to use a two-color focus, like so:

```css
/* ensure high-contrast mode still has an indicator */
outline: 2px transparent solid;

/* Apply a thick yellow box-shadow with 
   a thin dark blue indicator in the middle */
box-shadow: 0 0 0 2px #F9F9D1, 0 0 0 4px #396196, 0 0 4px 8px #F9F9D1;
``` 

From [Technique C40](https://www.w3.org/WAI/WCAG22/Techniques/css/C40).

Using two contrasting colors guarantees that the focus state will be visible, 
regardless of the background or surrounding colors.

## Troubleshooting

### Not enough contrasting pixels change

The [Success Criterion](https://w3c.github.io/wcag/understanding/focus-appearance.html) specifies a minimum area 
for the contrasting portion of the focus indicator, which is equivalent to a 2 CSS pixel border around the component.

From the requirements:

> "The easiest and most common way to meet this requirement is to use a solid outline around the component. 
> The outline must be at least 2px thick."

In practice, many websites use alternatives to this, such as a thick border along one edge. A problem with 
that approach is it is often dependent upon the length of that one edge, which for text links can vary dynamically.

See [Sara Soueidan](https://www.sarasoueidan.com/blog/focus-indicators/#2.-minimum-contrasting-area) for a good
write-up of this concept.

To comply with this Success Criterion, we recommend adding a 2px border around all edges.

Note an earlier draft of this Success Criterion has a more generous allowance here, which is not the case for the
final version.

### Elements appear to change in the browser

Focus states should be defined in CSS alone, and not require JavaScript to work. 

Try disabling JavaScript on the page, and see if focus is still visible. If it not, 
then the focus state won't work with assistive technologies that don't have a physical
keyboard, e.g. mobile phones.

Some more unusual means of implementing a focus state cannot be detected or measured
automatically. These include:

* Focus implemented via pseudo-elements - such as `::after` or `::before`. 
* Focus using `:focus-within` (JavaScript current provides no way to access these).
* Focus cascaded to child elements, e.g. a `<span>` inside an `<a>` tag. We detect
  some of these cases, but there are variations that we cannot detect.

Currently, there is no practical way to assess these focus states automatically.

### Elements over images not analyzed

Silktide cannot assess the contrast of elements that are over images. This is because
the contrast of an element is calculated by comparing the color of the element with the
color of the background. 

If the element is over an image, the background color is the
color of the image, which varies from pixel-to-pixel, and may vary further as the page
is resized, due to responsive design.

### Unexpected elements are focusable

You may be surprised to see tags like `<div>` or `<span>` being shown as focusable.
If an element has a `tabindex` of 0 or higher, it becomes focusable. Any HTML tag can be made 
focusable in this way, this is so that custom controls (e.g. your own drop-down menus, or 
sliders) can support keyboard navigation. [Learn more about tabindex on MDN](https://developer.mozilla.org/en-US/docs/Web/HTML/Global_attributes/tabindex).

## Further reading

* [WCAG 2.4.13](https://www.w3.org/WAI/WCAG22/Understanding/focus-appearance.html)
* [Minimum Contrasting Area explained (Sara Soueidan)](https://www.sarasoueidan.com/blog/focus-indicators/#2.-minimum-contrasting-area)

ensure-focus-appearance

January 2026

December 2025

Maersk

	Title / URL	Issues
	Contact \| Maerskwww.maersk.com/contact	23
	马士基 \| 综合集装箱物流和供应链服务www.maersk.com/zh-cn/	13
	Маерск \| Интегрированная Контейнерная Логистика и Услуги Цепочки Поставокwww.maersk.com/ru-ru/	13
	Maersk Türkiye \| Entegre Konteyner Lojistiğiwww.maersk.com/tr-tr/	13
	Maersk \| Servicios Integrados de Logística de Contenedores & Cadena de Suministrowww.maersk.com/es-mx/	13
	Maersk \| Servizi di Logistica Integrata dei Container & di Supply Chainwww.maersk.com/it-it/	13
	馬士基 \| 綜合性貨櫃物流與供應鏈服務www.maersk.com/zh-tw/	13
	Maersk \| Logistique de Conteneurs Intégrée & Services de Chaîne d’Approvisionnementwww.maersk.com/fr-fr/	13
	Maersk \| 통합 컨테이너 물류 및 공급망 서비스www.maersk.com/ko-kr/	13
	Maersk \| Logística Integrada de Contêineres e Serviços de Cadeia de Suprimentowww.maersk.com/pt-br/	13

Ensure controls clearly indicate when they are selected

Maersk

Where this issue has occurred