Accessibility

· 13 checks — Landmarks, headings, alt text, forms, and link quality rolled into one auditable list.

SCORE

GRADE

FIX

REVIEW

PASS

INFO

Checks

2 PASS 2 REVIEW 9 FIX

Landmark Structure

Action

2 landmarks

FIX

2 landmarks

No <main> landmark found

Screen reader users cannot quickly navigate to the primary content. Wrap your main content in <main>.

2 <nav> landmark(s) found

2 of 2 <nav> elements are unlabeled

Multiple navigations need aria-label to distinguish them for screen readers.

No banner (header) landmark

No contentinfo (footer) landmark

Skip navigation link is missing (WCAG 2.4.1)

Add a skip link as the first focusable element so keyboard users can bypass repeated navigation.

Page Structure — as a screen reader sees it

Screen reader users cannot quickly navigate to the primary content. Wrap your main content in <main>.

Why this matters

Without a <main> landmark, screen-reader users can't skip past the navigation to the page content — every page starts with re-reading the menu.

Learn more ▾

The <main> element marks the page's primary content area. Assistive tech offers a 'jump to main' shortcut — but only if <main> exists. Without it, every page navigation forces re-reading the header. Wrap your primary content in a single <main>.

Source: WAI-ARIA / WCAG 2.4.1

Multiple navigations need aria-label to distinguish them for screen readers.

Why this matters

Some <nav> elements lack aria-label — screen-reader users hear 'navigation' multiple times with no way to distinguish them.

Learn more ▾

When a page has multiple <nav> regions (primary, footer, breadcrumb), each needs aria-label or aria-labelledby. AT users navigate by landmark; identical 'navigation' announcements force them to enter each one to discover purpose.

Source: WAI-ARIA Authoring Practices

Add a skip link as the first focusable element so keyboard users can bypass repeated navigation.

Why this matters

Without a skip-nav link, keyboard users tab through every nav item before reaching content — every page, every visit.

Learn more ▾

WCAG 2.4.1 (Bypass Blocks) requires a mechanism to skip past repeated content. The standard implementation is a 'Skip to main content' link that's the first focusable element, visually hidden until focused. Three lines of HTML + four of CSS.

Source: WCAG 2.1 SC 2.4.1

Alt Text Quality

Action

2 of 23 images have issues

FIX

2 of 23 images have issues

2 image(s) missing alt attribute

Images without alt text are invisible to screen readers.

2 image-in-link without alt text

An image inside a link with no alt creates an empty link.

21 image(s) with good alt text

23 images 21 good alt text 2 missing

Issue	Count
missing	2 image(s)

Images without alt text are invisible to screen readers.

Why this matters

Each image without alt text is a WCAG 1.1.1 failure — invisible to screen-reader users, lost from Google Image Search.

Learn more ▾

WCAG 2.1 Level A requires text alternatives for non-decorative images. Empty alt='' is fine for decorative; meaningful images need descriptive text. Common fixes: CMS audit + bulk add, build-time linter (alt-text-required ESLint rule), CI gate on Lighthouse a11y score.

Source: WCAG 2.1 SC 1.1.1 / WebAIM Million Report

An image inside a link with no alt creates an empty link.

Why this matters

Image-only links with no alt create empty links — screen-reader users hear 'link' with no destination context.

Learn more ▾

An <a><img></a> with no img alt is the worst-case for accessibility: AT announces the link but can't describe where it goes. Either add alt to the image OR add aria-label to the link.

Source: WCAG 2.1 SC 2.4.4

Link & Button Quality

Action

16 issue(s) across 346 links and 10 buttons

FIX

16 issue(s) across 346 links and 10 buttons

12 link(s) with no accessible text

Links without text are announced as raw URLs by screen readers.

Got: /public/; https://facebook.com/ESOAstronomy; https://www.instagram.com/esoastronomy/; https://www.flickr.com/photos/esoastronomy/; https://www.youtube.com/ESOObservatory/; https://www.linkedin.com/company/european-southern-observatory; https://podcasts.apple.com/us/podcast/esocast-hd/id295471183; https://www.scribd.com/ESO_publications; https://bsky.app/profile/eso.org; https://mastodon.social/@esoastronomy (+2 more)

8 link(s) open in new tab without warning

Add '(opens in new tab)' to link text or aria-label.

Got: https://www.youtube.com/t/terms; https://www.youtube.com/channel/UCIhYoC2VIAJqCkoIWNHBQ3Q; https://support.google.com/youtube/answer/171780?hl=en-GB; https://support.brave.com/hc/en-us/signin?return_to=https%3A%2F%2Fsupport.bra…; https://support.google.com/chrome/bin/answer.py?hl=en&answer=95647&p=cpn_cookies; https://support.microsoft.com/en-us/windows/manage-cookies-in-microsoft-edge-…; https://support.mozilla.org/en-US/kb/Blocking cookies; https://docs.info.apple.com/article.html?path=Safari/3.0/en/9277.html

4 button(s) with no accessible text

Icon-only buttons need an aria-label so screen readers can announce them.

Got: button#searchbox-button; button.btn (#167 on page); button.slide-prev (#1046 on page); button.slide-next (#1048 on page)

326 link(s) with descriptive text

346 links

12 empty

0 generic text

8 new tab

4 empty buttons

Element	Text	Issue	Suggested Fix
/public/	(empty)	empty	Add link text or aria-label
https://supernova.eso.org/	ESO Supernova	img no alt	Add alt attribute to the image
https://www.eso.org/public/about-eso/vis…	Observatories	img no alt	Add alt attribute to the image
https://facebook.com/ESOAstronomy	(empty)	empty	Add link text or aria-label
https://www.instagram.com/esoastronomy/	(empty)	empty	Add link text or aria-label
https://www.flickr.com/photos/esoastrono…	(empty)	empty	Add link text or aria-label
https://www.youtube.com/ESOObservatory/	(empty)	empty	Add link text or aria-label
https://www.linkedin.com/company/europea…	(empty)	empty	Add link text or aria-label
https://podcasts.apple.com/us/podcast/es…	(empty)	empty	Add link text or aria-label
https://www.scribd.com/ESO_publications	(empty)	empty	Add link text or aria-label
https://bsky.app/profile/eso.org	(empty)	empty	Add link text or aria-label
https://mastodon.social/@esoastronomy	(empty)	empty	Add link text or aria-label
https://www.youtube.com/t/terms	YouTube	new tab	Add '(opens in new tab)' to text
https://www.youtube.com/channel/UCIhYoC2…	ESO’s official YouTube chann…	new tab	Add '(opens in new tab)' to text
https://support.google.com/youtube/answe…	embedding videos information p…	new tab	Add '(opens in new tab)' to text
https://support.brave.com/hc/en-us/signi…	Brave	new tab	Add '(opens in new tab)' to text
https://support.brave.com/hc/en-us/signi…	(empty)	empty	Add link text or aria-label
https://support.brave.com/hc/en-us/signi…	(empty)	empty	Add link text or aria-label
https://support.google.com/chrome/bin/an…	Chrome	new tab	Add '(opens in new tab)' to text
https://support.microsoft.com/en-us/wind…	Edge	new tab	Add '(opens in new tab)' to text
https://support.mozilla.org/en-US/kb/Blo…	Firefox	new tab	Add '(opens in new tab)' to text
https://docs.info.apple.com/article.html…	Safari	new tab	Add '(opens in new tab)' to text
<button>	(empty)	empty	Add button text or aria-label
<button>	(empty)	empty	Add button text or aria-label
<button>	(empty)	empty	Add button text or aria-label
<button>	(empty)	empty	Add button text or aria-label

332 links and buttons have descriptive text

Links without text are announced as raw URLs by screen readers.

/public/; https://facebook.com/ESOAstronomy; https://www.instagram.com/esoastronomy/; https://www.flickr.com/photos/esoastronomy/; https://www.youtube.com/ESOObservatory/; https://www.linkedin.com/company/european-southern-observatory; https://podcasts.apple.com/us/podcast/esocast-hd/id295471183; https://www.scribd.com/ESO_publications; https://bsky.app/profile/eso.org; https://mastodon.social/@esoastronomy (+2 more)

Why this matters

Links with no accessible text (empty <a></a>, image-only no alt, icon-only no aria-label) are unidentifiable to screen readers.

Source: WCAG 2.1 SC 2.4.4

Add '(opens in new tab)' to link text or aria-label.

https://www.youtube.com/t/terms; https://www.youtube.com/channel/UCIhYoC2VIAJqCkoIWNHBQ3Q; https://support.google.com/youtube/answer/171780?hl=en-GB; https://support.brave.com/hc/en-us/signin?return_to=https%3A%2F%2Fsupport.bra…; https://support.google.com/chrome/bin/answer.py?hl=en&answer=95647&p=cpn_cookies; https://support.microsoft.com/en-us/windows/manage-cookies-in-microsoft-edge-…; https://support.mozilla.org/en-US/kb/Blocking cookies; https://docs.info.apple.com/article.html?path=Safari/3.0/en/9277.html

Why this matters

Links with target="_blank" without rel="noopener" leak the originating page's window context — security and UX issue.

Learn more ▾

Without rel="noopener", the new tab can navigate the original tab via window.opener (tab-nabbing attack). Modern browsers default to noopener for target=_blank but only since recent versions. Always set rel="noopener noreferrer" explicitly.

Source: MDN target / OWASP

Icon-only buttons need an aria-label so screen readers can announce them.

button#searchbox-button; button.btn (#167 on page); button.slide-prev (#1046 on page); button.slide-next (#1048 on page)

Why this matters

Buttons with no accessible text (icon-only, no aria-label) can't be activated by voice control or understood by screen readers.

Source: WCAG 2.1 SC 4.1.2

404 Error Page

Action

HTTP 404, bare page

FIX

HTTP 404, bare page

Correct 404 status code returned

Got: HTTP 404

Bare server default 404 page

The 404 page has no custom styling. Users hitting a broken link see a generic error with no way to navigate back. Add a custom 404 page with your site navigation and a search bar.

404 Page Quality Default 404 Page

Status Code HTTP 404 ✓Page Title 404 Not Found ✓Custom Styling ✗Navigation ✗Homepage Link ✗Search Form ✗

Favicon & Branding

Action

2 icon(s) detected

FIX

2 icon(s) detected

favicon.ico present at site root

HTML icon links detected

No apple-touch-icon detected

iOS devices use this when users add your site to their home screen. Add <link rel='apple-touch-icon' sizes='180x180' href='/apple-touch-icon.png'>.

✓ favicon.ico Present

✓ PNG Icons Present

✗ Apple Touch Missing

✗ SVG Favicon Missing

✗ Manifest Icons Missing

✗ Multiple Sizes Missing

Web Manifest

Action

Not found

FIX

Not found

No web manifest found

No manifest at standard paths (/manifest.json, /site.webmanifest). A manifest is optional but enables PWA features like home screen installation and standalone display.

No web manifest found.

Dark Mode Support

Action

No dark mode signals

FIX

No dark mode signals

No dark mode signals detected

Consider adding CSS with @media (prefers-color-scheme: dark) and <meta name='color-scheme' content='light dark'>.

Detection limited to meta tags and inline styles

External CSS files may contain prefers-color-scheme rules not visible to this scan.

Dark ModeNo Dark Mode Detected

color-scheme meta Not set ✗Dark theme-color Not set ✗CSS indicators Not detected ✗

Detection limited to meta tags and inline styles.

Print Stylesheet

Action

No print styles

FIX

No print styles

No print-specific styles detected

When users print this page, they get the screen layout including navigation and non-essential elements. Add @media print rules to hide navigation and optimize layout for paper.

Print Stylesheet No Print Styles

Print stylesheet Not found ✗Inline @media print Not detected ✗

Navigation UX

Action

No navigation patterns

FIX

No navigation patterns

2 navigation landmark(s) detected

No breadcrumbs, search, or skip link detected

These navigation aids help users orient themselves and find content efficiently, especially on large sites.

Breadcrumbs

Skip Link

Labeled Navigation 2 <nav> element(s)

Hamburger Menu

Sticky Navigation Cannot reliably detect (CSS-based)

1 of 6 testable patterns navigation patterns detected. Limited navigation support. Consider adding breadcrumbs, search, and skip link.

Color Contrast (Screenshot)

Action

20 text elements analyzed, 15 fail WCAG AA

REVIEW

Analyzes text contrast against the actual rendered page, including background images, gradients, and overlays that CSS-based tools cannot detect.

5 pass 15 fail WCAG AA 1 pass AA only

h1 Our Stories

1.43:1

#000000

#232932

needs 3.0:1 (large text)

32px · bottom of viewport

h1 Our Telescopes

1.43:1

#000000

#232932

needs 3.0:1 (large text)

32px · bottom of viewport

h1 Visit Us

1.43:1

#000000

#232932

needs 3.0:1 (large text)

32px · bottom of viewport

h1 Our use of Cookies

1.43:1

#000000

#232932

needs 3.0:1 (large text)

32px · bottom of viewport

h1 ESO Cookies Policy

1.43:1

#000000

#232932

needs 3.0:1 (large text)

32px · bottom of viewport

h2 What are cookies?

1.43:1

#000000

#232932

needs 3.0:1 (large text)

24px · bottom of viewport

h2 Categories of cookies we use

1.43:1

#000000

#232932

needs 3.0:1 (large text)

24px · bottom of viewport

h2 How to manage cookies

1.43:1

#000000

#232932

needs 3.0:1 (large text)

24px · bottom of viewport

h2 Updates to the ESO Cookies Policy

1.43:1

#000000

#232932

needs 3.0:1 (large text)

24px · bottom of viewport

h2 Additional information

1.43:1

#000000

#232932

needs 3.0:1 (large text)

24px · bottom of viewport

title ESO

1.21:1

#000000

#1A1A1A

needs 4.5:1 (normal text)

16px · top of page (header area)

a International English

3.01:1

#000000

#2D5A95

needs 4.5:1 (normal text)

16px · top of page (header area)

a Czechia

3.00:1

#000000

#2C5A95

needs 4.5:1 (normal text)

16px · above the fold

a Deutsch (Schweiz)

1.39:1

#000000

#3B2002

needs 4.5:1 (normal text)

16px · above the fold · over background image/gradient

a Deutsch (Österreich)

1.00:1

#000000

needs 4.5:1 (normal text)

16px · above the fold

1 contrast failures on background images/gradients

These failures are invisible to CSS-based accessibility tools like Lighthouse. The text may be fine on a solid background, but fails when rendered over an image or gradient.

Show all checked elements (20)

Element	Ratio	Required	FG	BG	Result
h1 Our Stories	1.43:1	3.0:1	#000000	#232932	Fail
h1 Our Telescopes	1.43:1	3.0:1	#000000	#232932	Fail
h1 Visit Us	1.43:1	3.0:1	#000000	#232932	Fail
h1 Our use of Cookies	1.43:1	3.0:1	#000000	#232932	Fail
h1 ESO Cookies Policy	1.43:1	3.0:1	#000000	#232932	Fail
h2 What are cookies?	1.43:1	3.0:1	#000000	#232932	Fail
h2 Categories of cookie…	1.43:1	3.0:1	#000000	#232932	Fail
h2 How to manage cookie…	1.43:1	3.0:1	#000000	#232932	Fail
h2 Updates to the ESO C…	1.43:1	3.0:1	#000000	#232932	Fail
h2 Additional informati…	1.43:1	3.0:1	#000000	#232932	Fail
title ESO	1.21:1	4.5:1	#000000	#1A1A1A	Fail
span Select Language (en)	7.93:1	4.5:1	#000000	#9F9F9F	Pass
span (en)	19.60:1	4.5:1	#000000	#F7F7F7	Pass
a International Englis…	3.01:1	4.5:1	#000000	#2D5A95	Fail
a Czechia	3.00:1	4.5:1	#000000	#2C5A95	Fail
a Dansk	6.80:1	4.5:1	#000000	#8095AA	Pass
a Deutsch	12.39:1	4.5:1	#000000	#CAC6C4	Pass
a Deutsch (Belgien)	12.05:1	4.5:1	#000000	#C5C4C2	Pass
a Deutsch (Schweiz)	1.39:1	4.5:1	#000000	#3B2002	Fail
a Deutsch (Österreich…	1.00:1	4.5:1	#000000	#000000	Fail

Methodology: The top 20 text elements by font size were checked. Background color was sampled from the desktop screenshot using a 5-point pattern. WCAG 2.1 AA requires 4.5:1 for normal text and 3:1 for large text.

Lighthouse Accessibility Audits

Action

Score 71/100 — 8 failing, 19 passed

REVIEW

Accessibility

These checks highlight opportunities to improve the accessibility of your web app. Automatic detection can only detect a subset of issues and does not guarantee the accessibility of your web app, so manual testing is also encouraged.

ARIA

Focusable descendents within an `[aria-hidden="true"]` element prevent those interactive elements from being available to users of assistive technologies like screen readers. Learn how `aria-hidden` affects focusable elements.

Why this matters

Informational: a Permissions-Policy directive showing feature -> allowed origins.

Source: MDN Permissions-Policy

Failing Elements
ESO2517 — PRESS RELEASE Andreas Kaufer appointed as next ESO Director General T… `div#pr-carousel > div.slick-list > div.slick-track > div.slide`
ESO2604 — PRESS RELEASE A Solar System in the making? Two planets spotted formi… `div#pr-carousel > div.slick-list > div.slick-track > div.slide`
ESO2603 — PRESS RELEASE Largest image of its kind shows hidden chemistry at the… `div#pr-carousel > div.slick-list > div.slick-track > div.slide`
ESO2602 — PRESS RELEASE AES Andes announces cancellation of INNA, the industria… `div#pr-carousel > div.slick-list > div.slick-track > div.slide`
ESO2601 — PRESS RELEASE Astronomers surprised by mysterious shock wave around d… `div#pr-carousel > div.slick-list > div.slick-track > div.slide`
ESO2521 — PRESS RELEASE Construction begins on the first and largest gamma-ray … `div#pr-carousel > div.slick-list > div.slick-track > div.slide`
ESO2520 — PRESS RELEASE Unique shape of star’s explosion revealed just a day af… `div#pr-carousel > div.slick-list > div.slick-track > div.slide`
ESO2519 — PRESS RELEASE Laser trial run kickstarts new era of interferometry La… `div#pr-carousel > div.slick-list > div.slick-track > div.slide`
ESO2518 — PRESS RELEASE New image captures spooky bat signal in the sky A spook… `div#pr-carousel > div.slick-list > div.slick-track > div.slide`
ESO2517 — PRESS RELEASE Andreas Kaufer appointed as next ESO Director General T… `div#pr-carousel > div.slick-list > div.slick-track > div.slide`
ESO2605 — PRESS RELEASE First light for PoET: shining (sun)light on exoplanet r… `div#pr-carousel > div.slick-list > div.slick-track > div.slide`

These are opportunities to improve the usage of ARIA in your application which may enhance the experience for users of assistive technology, like a screen reader.

Names and labels

When a button doesn't have an accessible name, screen readers announce it as "button", making it unusable for users who rely on screen readers. Learn how to make buttons more accessible.

Why this matters