Lighthouse Desktop

· 0 checks — Desktop Lighthouse audit -- Performance, Accessibility, Best Practices, and SEO category breakdown.

SCORE

GRADE

FIX

REVIEW

PASS

INFO

Detailed Report

Audit breakdown by category with detailed findings.

Performance

Insights

Remove large, duplicate JavaScript modules from bundles to reduce unnecessary bytes consumed by network activity.

Why this matters

Performance issues directly impact user engagement and conversion rates.

Polyfills and transforms enable older browsers to use new JavaScript features. However, many aren't necessary for modern browsers. Consider modifying your JavaScript build process to not transpile Baseline features, unless you know you must support older browsers. Learn why most sites can deploy ES6+ code without transpiling

Why this matters

Performance issues directly impact user engagement and conversion rates.

3rd party code can significantly impact load performance. Reduce and defer loading of 3rd party code to prioritize your page's content.

Why this matters

Performance issues directly impact user engagement and conversion rates.

A long cache lifetime can speed up repeat visits to your page. Learn more about caching.

Why this matters

Performance issues directly impact user engagement and conversion rates.

Request	Cache TTL	Transfer Size
/sites/default/files/styles/large/public/2026-04/Kart-144...	0.0 ms	237.7 KiB
/sites/default/files/styles/large/public/2026-04/ATLAS-Ev...	0.0 ms	101.1 KiB
/sites/default/files/styles/large/public/2026-04/ATLAS_co...	0.0 ms	100.3 KiB
/sites/default/files/styles/large/public/2026-03/Toponium...	0.0 ms	91.9 KiB
/sites/default/files/styles/large/public/2026-04/collisio...	0.0 ms	62.8 KiB
/sites/default/files/styles/large/public/2026-03/Mosaic_s...	0.0 ms	32.3 KiB
/sites/default/files/styles/large/public/2026-04/IMG_7455...	0.0 ms	30.5 KiB
/sites/default/files/styles/large/public/2026-03/Image_Ch...	0.0 ms	16.7 KiB

Layout shifts occur when elements move absent any user interaction. Investigate the causes of layout shifts, such as elements being added, removed, or their fonts changing as the page loads.

Why this matters

Performance issues directly impact user engagement and conversion rates.

headings: [map[key:node label:Element subItemsHeading:map[key:extra] valueType:node] map[granularity:0.001 key:score label:Layout shift score subItemsHeading:map[key:cause valueType:text] valueType:numeric]]

items: [map[node:map[type:text value:Total] score:0.5469399999999999] map[node:map[boundingRect:map[bottom:3514 height:3474 left:0 right:1350 top:40 width:1350] lhId:page-30-BODY nodeLabel:body.page-node-193099 path:1,HTML,1,BODY selector:body.page-node-193099 snippet:<body class="page-node-193099 page-node-type-landing_page cern-theme-on path-frontpage …"> type:node] score:0.542963 subItems:map[items:[map[cause:Unsized image element extra:map[boundingRect:map[bottom:3223 height:40 left:105 right:145 top:3183 width:40] lhId:page-21-IMG nodeLabel:Facebook icon path:1,HTML,1,BODY,5,FOOTER,0,DIV,0,DIV,0,DIV,0,SECTION,0,DIV,1,DIV,0,P,0,A,0,IMG selector:div.field > p > a > img snippet:<img alt="Facebook icon" data-entity-type="file" data-entity-uuid="5da97013-d976-42e3-aaf3-c2cdf2683c3d" height="40" src="/sites/default/files/inline-images/lburdych/Facebook.png" width="40" loading="lazy"> type:node]]] type:subitems]] map[node:map[boundingRect:map[bottom:1001 height:60 left:0 right:1350 top:941 width:1350] lhId:page-31-DIV nodeLabel:div.layout > div.layout__region > div.field > div.field--item path:1,HTML,1,BODY,4,MAIN,1,DIV,0,DIV,0,DIV,2,DIV,0,DIV,0,DIV,1,DIV selector:div.layout > div.layout__region > div.field > div.field--item snippet:<div class="field--item"> type:node] score:0.001516 subItems:map[items:[map[cause:Unsized image element extra:map[boundingRect:map[bottom:3223 height:40 left:105 right:145 top:3183 width:40] lhId:page-21-IMG nodeLabel:Facebook icon path:1,HTML,1,BODY,5,FOOTER,0,DIV,0,DIV,0,DIV,0,SECTION,0,DIV,1,DIV,0,P,0,A,0,IMG selector:div.field > p > a > img snippet:<img alt="Facebook icon" data-entity-type="file" data-entity-uuid="5da97013-d976-42e3-aaf3-c2cdf2683c3d" height="40" src="/sites/default/files/inline-images/lburdych/Facebook.png" width="40" loading="lazy"> type:node]]] type:subitems]] map[node:map[boundingRect:map[bottom:1001 height:60 left:0 right:1350 top:941 width:1350] lhId:page-31-DIV nodeLabel:div.layout > div.layout__region > div.field > div.field--item path:1,HTML,1,BODY,4,MAIN,1,DIV,0,DIV,0,DIV,2,DIV,0,DIV,0,DIV,1,DIV selector:div.layout > div.layout__region > div.field > div.field--item snippet:<div class="field--item"> type:node] score:0.000743 subItems:map[items:[map[cause:Unsized image element extra:map[boundingRect:map[bottom:3223 height:40 left:105 right:145 top:3183 width:40] lhId:page-21-IMG nodeLabel:Facebook icon path:1,HTML,1,BODY,5,FOOTER,0,DIV,0,DIV,0,DIV,0,SECTION,0,DIV,1,DIV,0,P,0,A,0,IMG selector:div.field > p > a > img snippet:<img alt="Facebook icon" data-entity-type="file" data-entity-uuid="5da97013-d976-42e3-aaf3-c2cdf2683c3d" height="40" src="/sites/default/files/inline-images/lburdych/Facebook.png" width="40" loading="lazy"> type:node]]] type:subitems]] map[node:map[boundingRect:map[bottom:1001 height:60 left:0 right:1350 top:941 width:1350] lhId:page-31-DIV nodeLabel:div.layout > div.layout__region > div.field > div.field--item path:1,HTML,1,BODY,4,MAIN,1,DIV,0,DIV,0,DIV,2,DIV,0,DIV,0,DIV,1,DIV selector:div.layout > div.layout__region > div.field > div.field--item snippet:<div class="field--item"> type:node] score:0.000279 subItems:map[items:[map[cause:Unsized image element extra:map[boundingRect:map[bottom:3223 height:40 left:105 right:145 top:3183 width:40] lhId:page-21-IMG nodeLabel:Facebook icon path:1,HTML,1,BODY,5,FOOTER,0,DIV,0,DIV,0,DIV,0,SECTION,0,DIV,1,DIV,0,P,0,A,0,IMG selector:div.field > p > a > img snippet:<img alt="Facebook icon" data-entity-type="file" data-entity-uuid="5da97013-d976-42e3-aaf3-c2cdf2683c3d" height="40" src="/sites/default/files/inline-images/lburdych/Facebook.png" width="40" loading="lazy"> type:node]]] type:subitems]] map[node:map[boundingRect:map[bottom:1001 height:60 left:0 right:1350 top:941 width:1350] lhId:page-31-DIV nodeLabel:div.layout > div.layout__region > div.field > div.field--item path:1,HTML,1,BODY,4,MAIN,1,DIV,0,DIV,0,DIV,2,DIV,0,DIV,0,DIV,1,DIV selector:div.layout > div.layout__region > div.field > div.field--item snippet:<div class="field--item"> type:node] score:0.000192 subItems:map[items:[map[cause:Unsized image element extra:map[boundingRect:map[bottom:3223 height:40 left:105 right:145 top:3183 width:40] lhId:page-21-IMG nodeLabel:Facebook icon path:1,HTML,1,BODY,5,FOOTER,0,DIV,0,DIV,0,DIV,0,SECTION,0,DIV,1,DIV,0,P,0,A,0,IMG selector:div.field > p > a > img snippet:<img alt="Facebook icon" data-entity-type="file" data-entity-uuid="5da97013-d976-42e3-aaf3-c2cdf2683c3d" height="40" src="/sites/default/files/inline-images/lburdych/Facebook.png" width="40" loading="lazy"> type:node]]] type:subitems]]]

Consider setting font-display to swap or optional to ensure text is consistently visible. swap can be further optimized to mitigate layout shifts with font metric overrides.

Why this matters

Performance issues directly impact user engagement and conversion rates.

URL	Est Savings
framework.web.cern.ch/framework/3.0/fonts/sourcesanspro/regular.woff2	70 ms
framework.web.cern.ch/framework/3.0/fonts/sourcesanspro/light.woff2	70 ms
framework.web.cern.ch/framework/3.0/fonts/sourcesanspro/bold.woff2	70 ms
framework.web.cern.ch/framework/3.0/fonts/sourcesanspro/semibold.woff2	65 ms
framework.web.cern.ch/framework/3.0/fonts/open-sans/bold.woff2	60 ms
framework.web.cern.ch/framework/3.0/fonts/cern/cern.woff2	60 ms

A forced reflow occurs when JavaScript queries geometric properties (such as offsetWidth) after styles have been invalidated by a change to the DOM state. This can result in poor performance. Learn more about forced reflows and possible mitigations.

Why this matters

Performance issues directly impact user engagement and conversion rates.

headings: [map[key:source label:Top function call valueType:source-location] map[granularity:1 key:reflowTime label:Total reflow time valueType:ms]]

items: [map[reflowTime:34.517 source:map[column:22 line:19 type:source-location url:https://home.cern/core/misc/drupal.init.js?v=10.4.5 urlProvider:network]]]

headings: [map[key:source label:Source valueType:source-location] map[granularity:1 key:reflowTime label:Total reflow time valueType:ms]]

items: [map[reflowTime:22.521 source:map[column:79427 line:1 type:source-location url:https://home.cern/core/assets/vendor/jquery/jquery.min.js?v=3.7.1 urlProvider:network]] map[reflowTime:10.707 source:map[column:49615 line:1 type:source-location url:https://home.cern/core/assets/vendor/jquery/jquery.min.js?v=3.7.1 urlProvider:network]] map[reflowTime:0.396 source:map[column:50335 line:1 type:source-location url:https://home.cern/core/assets/vendor/jquery/jquery.min.js?v=3.7.1 urlProvider:network]] map[reflowTime:0.191 source:map[column:50393 line:1 type:source-location url:https://home.cern/core/assets/vendor/jquery/jquery.min.js?v=3.7.1 urlProvider:network]] map[reflowTime:0.199 source:map[column:50457 line:1 type:source-location url:https://home.cern/core/assets/vendor/jquery/jquery.min.js?v=3.7.1 urlProvider:network]] map[reflowTime:0.147 source:map[column:49637 line:1 type:source-location url:https://home.cern/core/assets/vendor/jquery/jquery.min.js?v=3.7.1 urlProvider:network]] map[reflowTime:0.356 source:map[column:51395 line:1 type:source-location url:https://home.cern/core/assets/vendor/jquery/jquery.min.js?v=3.7.1 urlProvider:network]]]

Reducing the download time of images can improve the perceived load time of the page and LCP. Learn more about optimizing image size

Why this matters

Performance issues directly impact user engagement and conversion rates.

	URL	Resource Size	Est Savings
div.owl-stage > div.owl-item > div.header-block > div.background-component `div.owl-stage > div.owl-item > div.header-block > div.background-component`	home.cern/sites/default/files/2026-04/Antimatter-3.png	5.0 MiB	4.0 MiB
div.owl-stage > div.owl-item > div.header-block > div.background-component `div.owl-stage > div.owl-item > div.header-block > div.background-component`	home.cern/sites/default/files/2026-04/g2-experiment_1.png	4.7 MiB	3.7 MiB
Plan your CERN visit `div.component-row__row > div.component-row__column > div.box-effects-wrapper > div#preview-card--8`	home.cern/sites/default/files/2025-12/202310-230_50_2_1.jpg	1.1 MiB	868.3 KiB
body.page-node-193099 > div#cern-global-loading-layout `body.page-node-193099 > div#cern-global-loading-layout`	home.cern/modules/custom/cern-loading/images/loader.gif	512.4 KiB	338.2 KiB
div.owl-stage > div.owl-item > div.header-block > div.background-component `div.owl-stage > div.owl-item > div.header-block > div.background-component`	home.cern/sites/default/files/2026-04/Toponium.png	1.3 MiB	275.0 KiB
W and Z bosons `div.component-row__row > div.component-row__column > div.box-effects-wrapper > div#preview-card--23`	home.cern/sites/default/files/2025-12/69576_1.jpeg	426.7 KiB	218.7 KiB
CERN levels up with new superconducting karts Engineering News 1 April, 2026 `carousel-cern-item.owl-item > div.carousel-cern-item > div.horizontal-boxes-row > div#preview-card--5`	/sites/default/files/styles/large/public/2026-04/Kart-144...	237.5 KiB	212.9 KiB
Neutral currents `div.component-row__row > div.component-row__column > div.box-effects-wrapper > div#preview-card--24`	home.cern/sites/default/files/2025-12/60100_2.jpeg	300.3 KiB	202.0 KiB
CERN and the environment `div#explore-cern > div.component-row__row > div.component-row__column > div#preview-card--11`	home.cern/sites/default/files/2025-12/OPEN-PHO-CIVIL-2023-001-6_0_1.jpeg	150.1 KiB	105.6 KiB
ATLAS sets record limits on Higgs boson’s sel... Physics News 22 April, 2026 `carousel-cern-item.owl-item > div.carousel-cern-item > div.horizontal-boxes-row > div#preview-card`	/sites/default/files/styles/large/public/2026-04/ATLAS-Ev...	100.9 KiB	84.2 KiB
ATLAS acts as a cosmic-ray laboratory Physics News 21 April, 2026 `carousel-cern-item.owl-item > div.carousel-cern-item > div.horizontal-boxes-row > div#preview-card--2`	/sites/default/files/styles/large/public/2026-04/ATLAS_co...	100.1 KiB	79.0 KiB
CMS strengthens the case for toponium Physics News 25 March, 2026 `carousel-cern-item.owl-item > div.carousel-cern-item > div.horizontal-boxes-row > div#preview-card--6`	/sites/default/files/styles/large/public/2026-03/Toponium...	91.8 KiB	70.7 KiB
Take an immersive tour of CERN's accelerators... `div.component-row__row > div.component-row__column > div.box-effects-wrapper > div#preview-card--9`	home.cern/sites/default/files/2025-12/Screenshot-vitual-tour_1.jpg	92.2 KiB	61.9 KiB
CMS looks deep inside quarks Physics News 16 April, 2026 `carousel-cern-item.owl-item > div.carousel-cern-item > div.horizontal-boxes-row > div#preview-card--3`	/sites/default/files/styles/large/public/2026-04/collisio...	62.6 KiB	41.5 KiB
X icon `div.field > p > a > img`	home.cern/sites/default/files/inline-images/lburdych/X.png	27.2 KiB	27.1 KiB
Instagram icon `div.field > p > a > img`	home.cern/sites/default/files/inline-images/lburdych/Instagram.png	25.7 KiB	25.6 KiB
home `div.site-info > div.site-info__logo > a > img`	home.cern/sites/default/files/logo/cern-logo.png	19.6 KiB	18.8 KiB
TikTok icon `div.field > p > a > img`	home.cern/sites/default/files/inline-images/lburdych/TikTok_0.png	18.8 KiB	18.6 KiB
Youtube icon `div.field > p > a > img`	home.cern/sites/default/files/inline-images/lburdych/Youtube.png	18.0 KiB	17.9 KiB
LinkedIn icon `div.field > p > a > img`	home.cern/sites/default/files/inline-images/lburdych/LinkedIn.png	14.4 KiB	14.3 KiB
The Large Hadron Collider `div.component-row__row > div.component-row__column > div.box-effects-wrapper > div#preview-card--20`	home.cern/sites/default/files/2025-12/CERN-AC-0911188-01_2.jpg	45.3 KiB	11.0 KiB
Facebook icon `div.field > p > a > img`	home.cern/sites/default/files/inline-images/lburdych/Facebook.png	11.0 KiB	11.0 KiB
Explore CERN's educational resources `div.component-row__row > div.component-row__column > div.box-effects-wrapper > div#preview-card--10`	/sites/default/files/2025-12/Artist Rasheedah Phillips fr...	263.8 KiB	10.6 KiB
The Higgs boson `div.component-row__row > div.component-row__column > div.box-effects-wrapper > div#preview-card--19`	home.cern/sites/default/files/2025-12/ATLAS-PHO-EVENTS-2014-010-1_1.jpg	43.2 KiB	5.7 KiB
CERN to host Europe’s flagship open access pu... At CERN News 26 March, 2026 `carousel-cern-item.owl-item > div.carousel-cern-item > div.horizontal-boxes-row > div#preview-card--3`	/sites/default/files/styles/large/public/2026-03/Mosaic_s...	32.1 KiB	4.1 KiB

Optimize LCP by making the LCP image discoverable from the HTML immediately, and avoiding lazy-loading

Why this matters

Performance issues directly impact user engagement and conversion rates.

lhId: page-1-DIV

nodeLabel: div.owl-stage > div.owl-item > div.header-block > div.background-component

path: 1,HTML,1,BODY,4,MAIN,1,DIV,0,DIV,0,DIV,2,DIV,0,DIV,0,DIV,0,DIV,0,DIV,0,DIV,0,DIV,0,DIV,0,DIV,0,DIV,0,DIV,0,DIV,2,DIV,0,DIV,2,DIV

selector: div.owl-stage > div.owl-item > div.header-block > div.background-component

snippet: <div class="background-component background__image" style="">

HTTP/2 and HTTP/3 offer many benefits over HTTP/1.1, such as multiplexing. Learn more about using modern HTTP.

Why this matters

Performance issues directly impact user engagement and conversion rates.

URL	Protocol
home.cern/	http/1.1
home.cern/modules/custom/cern-loading/css/cern_loading.css?tckkx1	http/1.1
framework.web.cern.ch/framework/3.0/js/owlcarousel/css/owl.carousel.css	http/1.1
framework.web.cern.ch/framework/3.0/js/owlcarousel/css/owl.theme.default.css	http/1.1
home.cern/core/misc/components/progress.module.css?tckkx1	http/1.1
home.cern/core/modules/system/css/components/align.module.css?tckkx1	http/1.1
home.cern/core/modules/system/css/components/fieldgroup.module.css?tckkx1	http/1.1
home.cern/core/modules/system/css/components/container-inline.module.css?tckkx1	http/1.1
home.cern/core/modules/system/css/components/clearfix.module.css?tckkx1	http/1.1
home.cern/core/modules/system/css/components/details.module.css?tckkx1	http/1.1
home.cern/core/modules/system/css/components/hidden.module.css?tckkx1	http/1.1
home.cern/core/modules/system/css/components/item-list.module.css?tckkx1	http/1.1
home.cern/core/modules/system/css/components/js.module.css?tckkx1	http/1.1
home.cern/core/modules/system/css/components/nowrap.module.css?tckkx1	http/1.1
/core/modules/system/css/components/position-container.mo...	http/1.1
home.cern/core/modules/system/css/components/reset-appearance.module.css?tckkx1	http/1.1
home.cern/core/modules/system/css/components/resize.module.css?tckkx1	http/1.1
home.cern/core/modules/system/css/components/system-status-counter.css?tckkx1	http/1.1
/core/modules/system/css/components/system-status-report-...	http/1.1
/core/modules/system/css/components/system-status-report-...	http/1.1
home.cern/core/modules/system/css/components/tablesort.module.css?tckkx1	http/1.1
home.cern/modules/custom/cern-toolbar/assets/css/screen.css?tckkx1	http/1.1
home.cern/modules/custom/cern-toolbar/assets/css/cookieconsent.css?tckkx1	http/1.1
/modules/custom/cern-components/patterns/molecules/agenda...	http/1.1
/modules/custom/cern-components/patterns/atoms/background...	http/1.1
/modules/custom/cern-components/patterns/molecules/header...	http/1.1
/modules/custom/cern-components/patterns/molecules/header...	http/1.1
/modules/custom/cern-components/patterns/molecules/margin...	http/1.1
/modules/custom/cern-components/patterns/molecules/menu/c...	http/1.1
/modules/custom/cern-components/patterns/molecules/previe...	http/1.1
/modules/custom/cern-components/patterns/molecules/row/cs...	http/1.1
home.cern/core/modules/views/css/views.module.css?tckkx1	http/1.1
home.cern/core/modules/layout_discovery/layouts/onecol/onecol.css?tckkx1	http/1.1
home.cern/modules/contrib/paragraphs/css/paragraphs.unpublished.css?tckkx1	http/1.1
home.cern/sites/default/themes/custom/cernbase/css/base.css?tckkx1	http/1.1
home.cern/sites/default/files/color/cernpublic-ac827e9a/colors.css?tckkx1	http/1.1
home.cern/sites/default/themes/custom/cernbase/css/layout.css?tckkx1	http/1.1
framework.web.cern.ch/framework/3.0/js/prism/prism.css	http/1.1
home.cern/sites/default/themes/custom/cernbase/css/components/footer.css?tckkx1	http/1.1
home.cern/sites/default/themes/custom/cernbase/css/components/header.css?tckkx1	http/1.1
/sites/default/themes/custom/cernbase/css/components/pagi...	http/1.1
home.cern/sites/default/themes/custom/cernbase/css/components/forms.css?tckkx1	http/1.1
home.cern/sites/default/themes/custom/cernbase/css/components/fields.css?tckkx1	http/1.1
/sites/default/themes/custom/cernbase/css/components/drop...	http/1.1
/sites/default/themes/custom/cernbase/css/components/prog...	http/1.1
/sites/default/themes/custom/cernbase/css/components/acco...	http/1.1
/sites/default/themes/custom/cernbase/css/components/soci...	http/1.1
framework.web.cern.ch/framework/3.0/js/colorbox/colorbox.css	http/1.1
home.cern/sites/default/themes/custom/cernbase/css/theme.css?tckkx1	http/1.1
home.cern/sites/default/themes/custom/cernbase/css/cookies.css?tckkx1	http/1.1
home.cern/sites/default/themes/custom/cernbase/css/viewspage.css?tckkx1	http/1.1
home.cern/sites/default/themes/custom/cernbase/css/views/faq-views.css?tckkx1	http/1.1
home.cern/sites/default/themes/custom/cernbase/css/views/agenda-views.css?tckkx1	http/1.1
home.cern/sites/default/themes/custom/cernbase/css/views/news-views.css?tckkx1	http/1.1
/sites/default/themes/custom/cernbase/css/views/stories-v...	http/1.1
/sites/default/themes/custom/cernbase/css/views/resources...	http/1.1
/sites/default/themes/custom/cernbase/css/views/taxonomie...	http/1.1
home.cern/sites/default/themes/custom/cernbase/css/views/search-views.css?tckkx1	http/1.1
home.cern/sites/default/themes/custom/cernbase/css/views/common-views.css?tckkx1	http/1.1
/sites/default/themes/custom/cernbase/css/views/generic-v...	http/1.1
home.cern/sites/default/themes/custom/cernpublic/css/layout.css?tckkx1	http/1.1
home.cern/sites/default/themes/custom/cernpublic/css/overrides.css?tckkx1	http/1.1
home.cern/sites/default/themes/custom/cernpublic/css/header.css?tckkx1	http/1.1
home.cern/sites/default/themes/custom/cernpublic/css/views.css?tckkx1	http/1.1
framework.web.cern.ch/framework/3.0/images/loader.gif	http/1.1
home.cern/sites/default/files/logo/cern-logo.png	http/1.1
home.cern/core/assets/vendor/jquery/jquery.min.js?v=3.7.1	http/1.1
home.cern/core/assets/vendor/underscore/underscore-min.js?v=1.13.7	http/1.1
home.cern/core/assets/vendor/once/once.min.js?v=1.0.1	http/1.1
/sites/default/files/languages/en_p5SjUX5jHQqdSjFPWYikWHz...	http/1.1
home.cern/core/misc/drupalSettingsLoader.js?v=10.4.5	http/1.1
home.cern/core/misc/drupal.js?v=10.4.5	http/1.1
home.cern/core/misc/drupal.init.js?v=10.4.5	http/1.1
home.cern/core/assets/vendor/tabbable/index.umd.min.js?v=6.2.0	http/1.1
home.cern/core/misc/progress.js?v=10.4.5	http/1.1
home.cern/themes/contrib/bootstrap/js/misc/progress.js?tckkx1	http/1.1
home.cern/core/assets/vendor/loadjs/loadjs.min.js?v=4.3.0	http/1.1
home.cern/core/misc/debounce.js?v=10.4.5	http/1.1
home.cern/core/misc/announce.js?v=10.4.5	http/1.1
home.cern/core/misc/message.js?v=10.4.5	http/1.1
home.cern/themes/contrib/bootstrap/js/misc/message.js?tckkx1	http/1.1
home.cern/core/misc/ajax.js?v=10.4.5	http/1.1
home.cern/themes/contrib/bootstrap/js/misc/ajax.js?tckkx1	http/1.1
/sites/default/themes/custom/cernbase/sass/bootstrap/java...	http/1.1
home.cern/themes/contrib/bootstrap/js/drupal.bootstrap.js?tckkx1	http/1.1
home.cern/themes/contrib/bootstrap/js/attributes.js?tckkx1	http/1.1
home.cern/themes/contrib/bootstrap/js/theme.js?tckkx1	http/1.1
home.cern/themes/contrib/bootstrap/js/popover.js?tckkx1	http/1.1
home.cern/themes/contrib/bootstrap/js/tooltip.js?tckkx1	http/1.1
home.cern/modules/custom/cern-loading/js/cern_loading.js?tckkx1	http/1.1
home.cern/modules/custom/cern-toolbar/assets/js/cern_toolbar.js?v=1.x	http/1.1
framework.web.cern.ch/framework/3.0/js/prism/prism.js	http/1.1
home.cern/sites/default/themes/custom/cernbase/js/cernbase.js?tckkx1	http/1.1
/sites/default/themes/custom/cernbase/js/components/socia...	http/1.1
home.cern/sites/default/themes/custom/cernbase/js/components/footer.js?tckkx1	http/1.1
home.cern/sites/default/themes/custom/cernbase/js/views/agenda-views.js?tckkx1	http/1.1
home.cern/sites/default/themes/custom/cernbase/js/views/faq-views.js?tckkx1	http/1.1
home.cern/sites/default/themes/custom/cernbase/js/views/news-views.js?tckkx1	http/1.1
/sites/default/themes/custom/cernbase/js/views/resources-...	http/1.1
home.cern/sites/default/themes/custom/cernbase/js/views/stories-views.js?tckkx1	http/1.1
/sites/default/themes/custom/cernbase/js/views/taxonomies...	http/1.1
home.cern/sites/default/themes/custom/cernbase/js/views/search-views.js?tckkx1	http/1.1
home.cern/sites/default/themes/custom/cernbase/js/views/common-views.js?tckkx1	http/1.1
home.cern/sites/default/themes/custom/cernbase/js/box-effects.js?tckkx1	http/1.1
framework.web.cern.ch/framework/3.0/js/colorbox/jquery.colorbox-min.js	http/1.1
framework.web.cern.ch/framework/3.0/js/scroll-magic/ScrollMagic.min.js	http/1.1
framework.web.cern.ch/framework/3.0/js/scroll-magic/text-effects.js	http/1.1
framework.web.cern.ch/framework/3.0/js/owlcarousel/js/owl.carousel.js	http/1.1
framework.web.cern.ch/framework/3.0/js/owlcarousel/js/owl.carousel2.thumbs.js	http/1.1
home.cern/sites/default/themes/custom/cernpublic/js/views_carousel.js?tckkx1	http/1.1
home.cern/sites/default/themes/custom/cernpublic/js/anchor-fix.js?tckkx1	http/1.1
home.cern/sites/default/modules/mathjax/js/config.js?v=10.4.5	http/1.1
home.cern/libraries/MathJax/MathJax.js?config=TeX-AMS-MML_HTMLorMML	http/1.1
home.cern/sites/default/modules/mathjax/js/setup.js?v=10.4.5	http/1.1
home.cern/modules/contrib/matomo/js/matomo.js?v=10.4.5	http/1.1
/modules/custom/cern-components/patterns/atoms/background...	http/1.1
/modules/custom/cern-components/patterns/molecules/header...	http/1.1
/modules/custom/cern-components/patterns/molecules/menu/j...	http/1.1
/modules/custom/cern-components/patterns/molecules/previe...	http/1.1
/modules/custom/cern-components/patterns/molecules/row/js...	http/1.1
home.cern/modules/custom/cern-loading/images/loader.gif	http/1.1
/sites/default/files/styles/large/public/2026-04/ATLAS-Ev...	http/1.1
/sites/default/files/styles/large/public/2026-04/ATLAS_co...	http/1.1
/sites/default/files/styles/large/public/2026-04/IMG_7455...	http/1.1
/sites/default/files/styles/large/public/2026-04/collisio...	http/1.1
/sites/default/files/styles/large/public/2026-03/Image_Ch...	http/1.1
home.cern/sites/default/files/2026-04/55182696113-0c4398702d-o-2_0.jpg	http/1.1
/sites/default/files/styles/large/public/2026-04/Kart-144...	http/1.1
/sites/default/files/styles/large/public/2026-03/Mosaic_s...	http/1.1
/sites/default/files/styles/large/public/2026-03/Toponium...	http/1.1
home.cern/sites/default/files/2025-12/202310-230_50_2_1.jpg	http/1.1
home.cern/sites/default/files/2025-12/Screenshot-vitual-tour_1.jpg	http/1.1
/sites/default/files/2025-12/Artist Rasheedah Phillips fr...	http/1.1
home.cern/sites/default/files/2025-12/OPEN-PHO-CIVIL-2023-001-6_0_1.jpeg	http/1.1
home.cern/sites/default/files/2025-12/CERN-EX-1212264-01_0_1.jpg	http/1.1
home.cern/sites/default/files/2025-12/ATLAS-PHO-EVENTS-2014-010-1_1.jpg	http/1.1
home.cern/sites/default/files/2025-12/CERN-AC-0911188-01_2.jpg	http/1.1
home.cern/sites/default/files/2025-12/CERN-EX-23296-1_1.jpg	http/1.1
home.cern/sites/default/files/2025-12/CERN-GE-9407011-31_1.jpg	http/1.1
home.cern/sites/default/files/2025-12/69576_1.jpeg	http/1.1
home.cern/sites/default/files/2025-12/60100_2.jpeg	http/1.1
framework.web.cern.ch/framework/3.0/fonts/sourcesanspro/regular.woff2	http/1.1
framework.web.cern.ch/framework/3.0/fonts/open-sans/bold.woff2	http/1.1
framework.web.cern.ch/framework/3.0/fonts/cern/cern.woff2	http/1.1
framework.web.cern.ch/framework/3.0/fonts/sourcesanspro/semibold.woff2	http/1.1
framework.web.cern.ch/framework/3.0/fonts/sourcesanspro/light.woff2	http/1.1
framework.web.cern.ch/framework/3.0/fonts/sourcesanspro/bold.woff2	http/1.1
home.cern/sites/default/files/inline-images/lburdych/Facebook.png	http/1.1
home.cern/sites/default/files/inline-images/lburdych/Instagram.png	http/1.1
home.cern/sites/default/files/inline-images/lburdych/TikTok_0.png	http/1.1
home.cern/sites/default/files/inline-images/lburdych/X.png	http/1.1
home.cern/sites/default/files/inline-images/lburdych/LinkedIn.png	http/1.1
home.cern/sites/default/files/inline-images/lburdych/Youtube.png	http/1.1
home.cern/sites/default/files/2026-04/g2-experiment_1.png	http/1.1
home.cern/sites/default/files/2026-04/Toponium.png	http/1.1
home.cern/sites/default/files/2026-04/Antimatter-3.png	http/1.1
home.cern/sites/default/themes/custom/cernpublic/favicon.ico	http/1.1

Avoid chaining critical requests by reducing the length of chains, reducing the download size of resources, or deferring the download of unnecessary resources to improve page load.

Why this matters

Performance issues directly impact user engagement and conversion rates.

description: [preconnect](https://developer.chrome.com/docs/lighthouse/performance/uses-rel-preconnect/) hints help the browser establish a connection earlier in the page load, saving time when the first request for that origin is made. The following are the origins that the page preconnected to.

title: Preconnected origins

value: no origins were preconnected

description: Add [preconnect](https://developer.chrome.com/docs/lighthouse/performance/uses-rel-preconnect/) hints to your most important origins, but try to use no more than 4.

title: Preconnect candidates

Requests are blocking the page's initial render, which may delay LCP. Deferring or inlining can move these network requests out of the critical path.

Why this matters

Performance issues directly impact user engagement and conversion rates.

URL	Transfer Size	Duration
home.cern/sites/default/themes/custom/cernpublic/css/blocks.css?tckkx1	0 B
home.cern/sites/default/themes/custom/cernpublic/css/views.css?tckkx1	1.1 KiB
home.cern/sites/default/themes/custom/cernpublic/css/header.css?tckkx1	470 B
/sites/default/themes/custom/cernbase/css/views/generic-v...	4.0 KiB
home.cern/sites/default/themes/custom/cernpublic/css/overrides.css?tckkx1	688 B
home.cern/sites/default/themes/custom/cernpublic/css/layout.css?tckkx1	1.6 KiB
home.cern/sites/default/themes/custom/cernbase/css/views/common-views.css?tckkx1	967 B
/sites/default/themes/custom/cernbase/css/views/taxonomie...	1.6 KiB
home.cern/sites/default/themes/custom/cernbase/css/views/search-views.css?tckkx1	1.6 KiB
home.cern/sites/default/themes/custom/cernbase/css/views/news-views.css?tckkx1	3.2 KiB
home.cern/sites/default/themes/custom/cernbase/css/views/agenda-views.css?tckkx1	3.5 KiB
/sites/default/themes/custom/cernbase/css/views/stories-v...	750 B
/sites/default/themes/custom/cernbase/css/views/resources...	3.2 KiB
home.cern/sites/default/themes/custom/cernbase/css/views/faq-views.css?tckkx1	1.8 KiB
home.cern/sites/default/themes/custom/cernbase/css/viewspage.css?tckkx1	477 B
home.cern/sites/default/themes/custom/cernbase/css/theme.css?tckkx1	5.6 KiB	84 ms
/sites/default/themes/custom/cernbase/css/components/acco...	860 B
home.cern/sites/default/themes/custom/cernbase/css/cookies.css?tckkx1	1008 B
/sites/default/themes/custom/cernbase/css/components/soci...	946 B
/sites/default/themes/custom/cernbase/css/components/prog...	1.0 KiB
/sites/default/themes/custom/cernbase/css/components/drop...	1.6 KiB
home.cern/sites/default/themes/custom/cernbase/css/components/header.css?tckkx1	3.2 KiB
home.cern/sites/default/themes/custom/cernbase/css/components/forms.css?tckkx1	2.3 KiB
home.cern/sites/default/themes/custom/cernbase/css/components/fields.css?tckkx1	970 B
/sites/default/themes/custom/cernbase/css/components/pagi...	1.3 KiB
home.cern/sites/default/themes/custom/cernbase/css/components/footer.css?tckkx1	1.8 KiB
home.cern/sites/default/themes/custom/cernbase/css/base.css?tckkx1	23.1 KiB	164 ms
home.cern/sites/default/files/color/cernpublic-ac827e9a/colors.css?tckkx1	5.8 KiB	84 ms
home.cern/modules/contrib/paragraphs/css/paragraphs.unpublished.css?tckkx1	314 B
home.cern/sites/default/themes/custom/cernbase/css/layout.css?tckkx1	3.0 KiB
home.cern/core/modules/layout_discovery/layouts/onecol/onecol.css?tckkx1	374 B
home.cern/core/modules/views/css/views.module.css?tckkx1	692 B
/modules/custom/cern-components/patterns/molecules/menu/c...	5.0 KiB	84 ms
/modules/custom/cern-components/patterns/molecules/row/cs...	2.3 KiB
/modules/custom/cern-components/patterns/molecules/margin...	438 B
/modules/custom/cern-components/patterns/molecules/previe...	2.8 KiB
/modules/custom/cern-components/patterns/molecules/header...	1.1 KiB
/modules/custom/cern-components/patterns/molecules/header...	2.9 KiB
/modules/custom/cern-components/patterns/atoms/background...	844 B
/modules/custom/cern-components/patterns/molecules/agenda...	2.6 KiB
home.cern/modules/custom/cern-toolbar/assets/css/cookieconsent.css?tckkx1	781 B
home.cern/modules/custom/cern-toolbar/assets/css/screen.css?tckkx1	2.0 KiB
home.cern/core/modules/system/css/components/tablesort.module.css?tckkx1	623 B
/core/modules/system/css/components/system-status-report-...	513 B
framework.web.cern.ch/framework/3.0/js/colorbox/colorbox.css	1.5 KiB	211 ms
framework.web.cern.ch/framework/3.0/js/prism/prism.css	2.3 KiB	211 ms
framework.web.cern.ch/framework/3.0/js/owlcarousel/css/owl.theme.default.css	949 B	211 ms
framework.web.cern.ch/framework/3.0/js/owlcarousel/css/owl.carousel.css	1.5 KiB	211 ms
/core/modules/system/css/components/system-status-report-...	815 B
home.cern/core/modules/system/css/components/reset-appearance.module.css?tckkx1	507 B
home.cern/core/modules/system/css/components/system-status-counter.css?tckkx1	1023 B
/core/modules/system/css/components/position-container.mo...	352 B
home.cern/core/modules/system/css/components/resize.module.css?tckkx1	528 B
home.cern/core/modules/system/css/components/nowrap.module.css?tckkx1	353 B
home.cern/core/modules/system/css/components/js.module.css?tckkx1	920 B
home.cern/core/modules/system/css/components/item-list.module.css?tckkx1	545 B
home.cern/core/modules/system/css/components/hidden.module.css?tckkx1	955 B
home.cern/core/modules/system/css/components/details.module.css?tckkx1	385 B
home.cern/core/modules/system/css/components/container-inline.module.css?tckkx1	533 B	124 ms
home.cern/core/modules/system/css/components/clearfix.module.css?tckkx1	565 B	124 ms
home.cern/core/modules/system/css/components/align.module.css?tckkx1	742 B	124 ms
home.cern/core/modules/system/css/components/fieldgroup.module.css?tckkx1	352 B	124 ms
home.cern/core/misc/components/progress.module.css?tckkx1	1.1 KiB	124 ms
home.cern/modules/custom/cern-loading/css/cern_loading.css?tckkx1	453 B

These insights are also available in the Chrome DevTools Performance Panel - record a trace to view more detailed information.

Time to Interactive is the amount of time it takes for the page to become fully interactive. Learn more about the Time to Interactive metric.

Why this matters

Performance issues directly impact user engagement and conversion rates.

TTI

These are the largest layout shifts observed on the page. Each table item represents a single layout shift, and shows the element that shifted the most. Below each item are possible root causes that led to the layout shift. Some of these layout shifts may not be included in the CLS metric value due to windowing. Learn how to improve CLS

Why this matters

Performance issues directly impact user engagement and conversion rates.

Element	Layout shift score
body.page-node-193099 `body.page-node-193099`	0.543
div.layout > div.layout__region > div.field > div.field--item `div.layout > div.layout__region > div.field > div.field--item`	0.002
div.layout > div.layout__region > div.field > div.field--item `div.layout > div.layout__region > div.field > div.field--item`	0.001
div.layout > div.layout__region > div.field > div.field--item `div.layout > div.layout__region > div.field > div.field--item`	0.000
div.layout > div.layout__region > div.field > div.field--item `div.layout > div.layout__region > div.field > div.field--item`	0.000
div.layout > div.layout__region > div.field > div.field--item `div.layout > div.layout__region > div.field > div.field--item`	0.000
div.layout > div.layout__region > div.field > div.field--item `div.layout > div.layout__region > div.field > div.field--item`	0.000
div.layout > div.layout__region > div.field > div.field--item `div.layout > div.layout__region > div.field > div.field--item`	0.000
div.layout > div.layout__region > div.field > div.field--item `div.layout > div.layout__region > div.field > div.field--item`	0.000
div.layout > div.layout__region > div.field > div.field--item `div.layout > div.layout__region > div.field > div.field--item`	0.000
19 April, 2026 `div.component-preview-cards__box_wrapper > div.component-preview-cards__box > div.preview-cards__subtext > div.preview-card__date`	0.000
div.layout > div.layout__region > div.field > div.field--item `div.layout > div.layout__region > div.field > div.field--item`	0.000
div.layout > div.layout__region > div.field > div.field--item `div.layout > div.layout__region > div.field > div.field--item`	0.000
div.layout > div.layout__region > div.field > div.field--item `div.layout > div.layout__region > div.field > div.field--item`	0.000
div.layout > div.layout__region > div.field > div.field--item `div.layout > div.layout__region > div.field > div.field--item`	0.000

Diagnostics

Minifying CSS files can reduce network payload sizes. Learn how to minify CSS.

Why this matters

Performance issues directly impact user engagement and conversion rates.

Estimated savings: 0.0 ms 4.3 KiB

URL	Transfer Size	Est Savings
home.cern/sites/default/themes/custom/cernbase/css/base.css?tckkx1	23.1 KiB	4.3 KiB

Minifying JavaScript files can reduce payload sizes and script parse time. Learn how to minify JavaScript.

Why this matters

Performance issues directly impact user engagement and conversion rates.

Estimated savings: 0.0 ms 26.9 KiB

URL	Transfer Size	Est Savings
home.cern/core/misc/ajax.js?v=10.4.5	17.0 KiB	11.9 KiB
framework.web.cern.ch/framework/3.0/js/owlcarousel/js/owl.carousel.js	18.5 KiB	7.2 KiB
home.cern/core/misc/drupal.js?v=10.4.5	6.1 KiB	4.8 KiB
home.cern/themes/contrib/bootstrap/js/drupal.bootstrap.js?tckkx1	4.9 KiB	2.9 KiB

Reduce unused rules from stylesheets and defer CSS not used for above-the-fold content to decrease bytes consumed by network activity. Learn how to reduce unused CSS.

Why this matters

Performance issues directly impact user engagement and conversion rates.

Estimated savings: 0.0 ms 21.6 KiB

URL	Transfer Size	Est Savings
home.cern/sites/default/themes/custom/cernbase/css/base.css?tckkx1	22.8 KiB	21.6 KiB

Large network payloads cost users real money and are highly correlated with long load times. Learn how to reduce payload sizes.

Why this matters

Performance issues directly impact user engagement and conversion rates.

URL	Transfer Size
home.cern/sites/default/files/2026-04/Antimatter-3.png	5.0 MiB
home.cern/sites/default/files/2026-04/g2-experiment_1.png	4.7 MiB
home.cern/sites/default/files/2026-04/Toponium.png	1.3 MiB
home.cern/sites/default/files/2025-12/202310-230_50_2_1.jpg	1.1 MiB
home.cern/sites/default/files/2026-04/55182696113-0c4398702d-o-2_0.jpg	677.0 KiB
framework.web.cern.ch/framework/3.0/images/loader.gif	512.8 KiB
home.cern/modules/custom/cern-loading/images/loader.gif	512.7 KiB
home.cern/sites/default/files/2025-12/69576_1.jpeg	427.0 KiB
home.cern/sites/default/files/2025-12/60100_2.jpeg	300.6 KiB
/sites/default/files/2025-12/Artist Rasheedah Phillips fr...	264.0 KiB

Set an explicit width and height on image elements to reduce layout shifts and improve CLS. Learn how to set image dimensions

Why this matters

Performance issues directly impact user engagement and conversion rates.

	URL
home `div.site-info > div.site-info__logo > a > img`	home.cern/sites/default/files/logo/cern-logo.png

More information about the performance of your application. These numbers don't directly affect the Performance score.

●Max Potential First Input Delay 100 ms

●Document request latency

●Optimize DOM size

●LCP breakdown

●Optimize viewport for mobile

●Reduce unused JavaScript

●JavaScript execution time 0.2 s

●Minimizes main-thread work 0.9 s

●Avoid long main-thread tasks 1 long task found

●Avoid non-composited animations 7 animated elements found

●Page didn't prevent back/forward cache restoration

●Network Requests

●Network Round Trip Times 30 ms

●Server Backend Latencies 20 ms

●Tasks

●Diagnostics

●Metrics

●Screenshot Thumbnails

●Final Screenshot

●Script Treemap Data

●Resources Summary

●Avoid multiple page redirects

●Initial server response time was short Root document took 70 ms

○INP breakdown

○User Timing marks and measures

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

Each ARIA `role` supports a specific subset of `aria-*` attributes. Mismatching these invalidates the `aria-*` attributes. Learn how to match ARIA attributes to their roles.

Why this matters

Performance issues directly impact user engagement and conversion rates.

Failing Elements
\| EN `div#bs-example-navbar-collapse-1 > ul.nav > li.dropdown > a.dropdown-toggle`

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

Performance issues directly impact user engagement and conversion rates.

Failing Elements
div.views-element-container > div.events-collision > div.view-content > button.bubbly-button `div.views-element-container > div.events-collision > div.view-content > button.bubbly-button`

Link text (and alternate text for images, when used as links) that is discernible, unique, and focusable improves the navigation experience for screen reader users. Learn how to make links accessible.

Why this matters

Performance issues directly impact user engagement and conversion rates.

Failing Elements
div.carousel-cern-item > div.horizontal-boxes-row > div#preview-card > a.box-link `div.carousel-cern-item > div.horizontal-boxes-row > div#preview-card > a.box-link`
div.carousel-cern-item > div.horizontal-boxes-row > div#preview-card--2 > a.box-link `div.carousel-cern-item > div.horizontal-boxes-row > div#preview-card--2 > a.box-link`
div.carousel-cern-item > div.horizontal-boxes-row > div#preview-card > a.box-link `div.carousel-cern-item > div.horizontal-boxes-row > div#preview-card > a.box-link`
div.carousel-cern-item > div.horizontal-boxes-row > div#preview-card--3 > a.box-link `div.carousel-cern-item > div.horizontal-boxes-row > div#preview-card--3 > a.box-link`
div.carousel-cern-item > div.horizontal-boxes-row > div#preview-card--2 > a.box-link `div.carousel-cern-item > div.horizontal-boxes-row > div#preview-card--2 > a.box-link`
div.carousel-cern-item > div.horizontal-boxes-row > div#preview-card--4 > a.box-link `div.carousel-cern-item > div.horizontal-boxes-row > div#preview-card--4 > a.box-link`
div.carousel-cern-item > div.horizontal-boxes-row > div#preview-card--5 > a.box-link `div.carousel-cern-item > div.horizontal-boxes-row > div#preview-card--5 > a.box-link`
div.carousel-cern-item > div.horizontal-boxes-row > div#preview-card--3 > a.box-link `div.carousel-cern-item > div.horizontal-boxes-row > div#preview-card--3 > a.box-link`
div.carousel-cern-item > div.horizontal-boxes-row > div#preview-card--6 > a.box-link `div.carousel-cern-item > div.horizontal-boxes-row > div#preview-card--6 > a.box-link`
div.component-row__column > div.box-effects-wrapper > div#preview-card--8 > a.box-link `div.component-row__column > div.box-effects-wrapper > div#preview-card--8 > a.box-link`
div.component-row__column > div.box-effects-wrapper > div#preview-card--9 > a.box-link `div.component-row__column > div.box-effects-wrapper > div#preview-card--9 > a.box-link`
div.component-row__column > div.box-effects-wrapper > div#preview-card--10 > a.box-link `div.component-row__column > div.box-effects-wrapper > div#preview-card--10 > a.box-link`
div.component-row__row > div.component-row__column > div#preview-card--11 > a.box-link `div.component-row__row > div.component-row__column > div#preview-card--11 > a.box-link`
div.component-row__row > div.component-row__column > div#preview-card--12 > a.box-link `div.component-row__row > div.component-row__column > div#preview-card--12 > a.box-link`
div.component-row__column > div.box-effects-wrapper > div#preview-card--19 > a.box-link `div.component-row__column > div.box-effects-wrapper > div#preview-card--19 > a.box-link`
div.component-row__column > div.box-effects-wrapper > div#preview-card--20 > a.box-link `div.component-row__column > div.box-effects-wrapper > div#preview-card--20 > a.box-link`
div.component-row__column > div.box-effects-wrapper > div#preview-card--21 > a.box-link `div.component-row__column > div.box-effects-wrapper > div#preview-card--21 > a.box-link`
div.component-row__column > div.box-effects-wrapper > div#preview-card--22 > a.box-link `div.component-row__column > div.box-effects-wrapper > div#preview-card--22 > a.box-link`
div.component-row__column > div.box-effects-wrapper > div#preview-card--23 > a.box-link `div.component-row__column > div.box-effects-wrapper > div#preview-card--23 > a.box-link`
div.component-row__column > div.box-effects-wrapper > div#preview-card--24 > a.box-link `div.component-row__column > div.box-effects-wrapper > div#preview-card--24 > a.box-link`

These are opportunities to improve the semantics of the controls in your application. This may enhance the experience for users of assistive technology, like a screen reader.

Contrast

Low-contrast text is difficult or impossible for many users to read. Learn how to provide sufficient color contrast.

Why this matters

Performance issues directly impact user engagement and conversion rates.

Failing Elements
Copyright `body.page-node-193099 > footer > div.copy-wrapper > a`

These are opportunities to improve the legibility of your content.

Navigation

Properly ordered headings that do not skip levels convey the semantic structure of the page, making it easier to navigate and understand when using assistive technologies. Learn more about heading order.

Why this matters

Performance issues directly impact user engagement and conversion rates.

Failing Elements
ATLAS sets record limits on Higgs boson’s sel... `div.component-preview-cards__box_wrapper > div.component-preview-cards__box > div.preview-card__title > h3.standard-title`
Plan your CERN visit `div.component-preview-cards__box_wrapper > div.component-preview-cards__box > div.preview-card__title > h3`
Axiverse Lampposts `div.agenda-box-pattern > div.agenda-box-pattern__box-wrapper > div.agenda-box-link > h3`
The Higgs boson `div.component-preview-cards__box_wrapper > div.component-preview-cards__box > div.preview-card__title > h3`

These are opportunities to improve keyboard navigation in your application.

○Interactive controls are keyboard focusable

○Interactive elements indicate their purpose and state

○The page has a logical tab order

○Visual order on the page follows DOM order

○User focus is not accidentally trapped in a region

○The user's focus is directed to new content added to the page

○HTML5 landmark elements are used to improve navigation

○Offscreen content is hidden from assistive technology

○Custom controls have associated labels

○Custom controls have ARIA roles

●`[aria-hidden="true"]` is not present on the document `<body>`

●`[role]`s have all required `[aria-*]` attributes

●`[role]` values are valid

●`[aria-*]` attributes have valid values

●`[aria-*]` attributes are valid and not misspelled

●Image elements have `[alt]` attributes

●`[user-scalable="no"]` is not used in the `<meta name="viewport">` element and the `[maximum-scale]` attribute is not less than 5.

●ARIA attributes are used as specified for the element's role

●`[aria-hidden="true"]` elements do not contain focusable descendents

●Elements use only permitted ARIA attributes

●Document has a `<title>` element

●`<html>` element has a `[lang]` attribute

●`<html>` element has a valid value for its `[lang]` attribute

●Links are distinguishable without relying on color.

●Lists contain only `<li>` elements and script supporting elements (`<script>` and `<template>`).

●List items (`<li>`) are contained within `<ul>`, `<ol>` or `<menu>` parent elements

●No element has a `[tabindex]` value greater than 0

●Touch targets have sufficient size and spacing.

●Document has a main landmark.

●Deprecated ARIA roles were not used

●Identical links have the same purpose.

○`[accesskey]` values are unique

○`button`, `link`, and `menuitem` elements have accessible names

○Elements with `role="dialog"` or `role="alertdialog"` have accessible names.

○ARIA input fields have accessible names

○ARIA `meter` elements have accessible names

○ARIA `progressbar` elements have accessible names

○Elements with an ARIA `[role]` that require children to contain a specific `[role]` have all required children.

○`[role]`s are contained by their required parent element

○Elements with the `role=text` attribute do not have focusable descendents.

○ARIA toggle fields have accessible names

○ARIA `tooltip` elements have accessible names

○ARIA `treeitem` elements have accessible names

○The page contains a heading, skip link, or landmark region

○`<dl>`'s contain only properly-ordered `<dt>` and `<dd>` groups, `<script>`, `<template>` or `<div>` elements.

○Definition list items are wrapped in `<dl>` elements

○ARIA IDs are unique

○No form fields have multiple labels

○`<frame>` or `<iframe>` elements have a title

○`<html>` element has an `[xml:lang]` attribute with the same base language as the `[lang]` attribute.

○Input buttons have discernible text.

○`<input type="image">` elements have `[alt]` text

○Form elements have associated labels

○The document does not use `<meta http-equiv="refresh">`

○`<object>` elements have alternate text

○Select elements have associated label elements.

○Skip links are focusable.

○Cells in a `<table>` element that use the `[headers]` attribute refer to table cells within the same table.

○`<th>` elements and elements with `[role="columnheader"/"rowheader"]` have data cells they describe.

○`[lang]` attributes have a valid value

○`<video>` elements contain a `<track>` element with `[kind="captions"]`

○Tables have different content in the summary attribute and `<caption>`.

○All heading elements contain content.

○Uses ARIA roles only on compatible elements

○Image elements do not have `[alt]` attributes that are redundant text.

○Elements with visible text labels have matching accessible names.

○Tables use `<caption>` instead of cells with the `[colspan]` attribute to indicate a caption.

○`<td>` elements in a large `<table>` have one or more table headers.

Best Practices

General

Errors logged to the console indicate unresolved problems. They can come from network request failures and other browser concerns. Learn more about this errors in console diagnostic audit

Why this matters

Performance issues directly impact user engagement and conversion rates.

Source	Description
home.cern/libraries/MathJax/MathJax.js?config=TeX-AMS-MML_HTMLorMML	`Failed to load resource: the server responded with a status of 404 (Not Found)`
home.cern/	`Refused to apply style from 'https://home.cern/sites/default/themes/custom/cernpublic/css/blocks.css?tckkx1' because its MIME type ('text/html') is not a supported stylesheet MIME type, and strict MIME checking is enabled.`
home.cern/	`Refused to execute script from 'https://home.cern/libraries/MathJax/MathJax.js?config=TeX-AMS-MML_HTMLorMML' because its MIME type ('text/html') is not executable, and strict MIME type checking is enabled.`

●Uses HTTPS

●Avoids deprecated APIs

●Avoids third-party cookies

●Allows users to paste into input fields

●Avoids requesting the geolocation permission on page load

●Avoids requesting the notification permission on page load

●Displays images with correct aspect ratio

●Serves images with appropriate resolution

●Page has the HTML doctype

●Properly defines charset

●No issues in the `Issues` panel in Chrome Devtools

●Ensure CSP is effective against XSS attacks

●Use a strong HSTS policy

●Ensure proper origin isolation with COOP

●Mitigate DOM-based XSS with Trusted Types

●Detected JavaScript libraries

●Page has valid source maps

○Redirects HTTP traffic to HTTPS

○Mitigate clickjacking with XFO or CSP

100

SEO

These checks ensure that your page is following basic search engine optimization advice. There are many additional factors Lighthouse does not score here that may affect your search ranking, including performance on Core Web Vitals. Learn more about Google Search Essentials.

○Structured data is valid

●Page isn’t blocked from indexing

●Document has a `<title>` element

●Document has a meta description

●Page has successful HTTP status code

●Links have descriptive text

●Links are crawlable

●robots.txt is valid

●Image elements have `[alt]` attributes

●Document has a valid `hreflang`

●Document has a valid `rel=canonical`