Lighthouse Mobile

· 0 checks — Mobile 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
www.mit.edu/themes/mit/assets/js/main.js?t5zcu8	0.0 ms	367.2 KiB
www.mit.edu/files/images/202604/MIT-PhytoFastFood-SL.jpg	0.0 ms	322.1 KiB
www.mit.edu/files/images/202604/MIT-Insulin-Implant-SLdw.jpg	0.0 ms	89.8 KiB
www.mit.edu/files/images/202505/MIT-This-is-MIT-SLsub_0_0.jpg	0.0 ms	84.6 KiB
www.mit.edu/themes/mit/assets/css/main.css?t5zcu8	0.0 ms	75.1 KiB
www.mit.edu/files/images/202603/MIT_battery-dendrites-home.jpg	0.0 ms	60.6 KiB
www.mit.edu/files/images/202505/Final-Thumbnails-Filehm.jpg	0.0 ms	58.6 KiB
www.mit.edu/files/images/202603/MIT-Hand-Tracker-SLsub.jpg	0.0 ms	48.6 KiB
www.mit.edu/files/images/202604/artemis-ii-launch-nasa-00_dw.jpg	0.0 ms	45.2 KiB
www.mit.edu/themes/mit/assets/js/modernizr.js?t5zcu8	0.0 ms	6.1 KiB
www.mit.edu/themes/mit/assets/js/SpotlightsRecent.d6a3aa4b97b1659f1bbb.js	0.0 ms	5.2 KiB
www.mit.edu/themes/mit/assets/js/Notification.11fc703b491d61aecf97.js	0.0 ms	3.7 KiB
/themes/mit/assets/js/SpotlightsExploreMoreLink.24ae33fb1...	0.0 ms	1.7 KiB
/p.css?s=1&k=uby1wjv&ht=tk&f=39496.39497.39498.39499.3950...	604800.0 s	172 B

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:0.20804] map[node:map[boundingRect:map[bottom:1233 height:620 left:0 right:412 top:613 width:412] lhId:page-7-DIV nodeLabel:EAPS scientists found that as sea surface temperatures rise, phytoplankton in p… path:1,HTML,1,BODY,5,MAIN,2,DIV,0,DIV,0,ARTICLE,0,DIV selector:div#main > div.spotlight__width > article.spotlight > div.spotlight-inner snippet:<div class="spotlight-inner"> type:node] score:0.180626] map[node:map[boundingRect:map[bottom:1233 height:620 left:0 right:412 top:613 width:412] lhId:page-7-DIV nodeLabel:EAPS scientists found that as sea surface temperatures rise, phytoplankton in p… path:1,HTML,1,BODY,5,MAIN,2,DIV,0,DIV,0,ARTICLE,0,DIV selector:div#main > div.spotlight__width > article.spotlight > div.spotlight-inner snippet:<div class="spotlight-inner"> type:node] score:0.027414]]

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
/af/174ae3/00000000000000007735bb5a/31/l?primer=7cdcb44be...	95 ms
/af/216c2e/00000000000000007735bb6a/31/l?primer=7cdcb44be...	90 ms
/af/c002e2/00000000000000007735bb32/31/l?primer=7cdcb44be...	80 ms
/af/2288cb/00000000000000007735bb39/31/l?primer=7cdcb44be...	55 ms
/af/912d1e/00000000000000007735bb33/31/l?primer=7cdcb44be...	45 ms

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
A cartoon cereal box is called “Phyt-O’s: the phytoplankton of the future” and … `div.spotlight__media > figure.spotlight__figure > a.spotlight__figure-link > img.spotlight__img`	www.mit.edu/files/images/202604/MIT-PhytoFastFood-SL.jpg	321.6 KiB	265.2 KiB
Kilian Court `div.spotlight-addl-content-block--inner > div.spotlight-addl-content-block--img > a > img`	www.mit.edu/files/images/202505/MIT-This-is-MIT-SLsub_0_0.jpg	84.1 KiB	45.0 KiB
Implant parts arranged like a a flower. `div.spotlight-addl-content-block--inner > div.spotlight-addl-content-block--img > a > img`	www.mit.edu/files/images/202604/MIT-Insulin-Implant-SLdw.jpg	89.3 KiB	43.3 KiB
Killian columns `div.spotlight-addl-content-block--inner > div.spotlight-addl-content-block--img > a > img`	www.mit.edu/files/images/202505/Final-Thumbnails-Filehm.jpg	58.1 KiB	19.0 KiB
Light shows the dendrite cracks. A bowtie-shaped pattern can be seen at the cra… `div.spotlight-addl-content-block--inner > div.spotlight-addl-content-block--img > a > img`	www.mit.edu/files/images/202603/MIT_battery-dendrites-home.jpg	60.2 KiB	14.2 KiB
A researcher training a robotic hand `div.spotlight-addl-content-block--inner > div.spotlight-addl-content-block--img > a > img`	www.mit.edu/files/images/202603/MIT-Hand-Tracker-SLsub.jpg	48.1 KiB	9.1 KiB
Artemis spacecraft launches, with lots of smoke. `div.spotlight-addl-content-block--inner > div.spotlight-addl-content-block--img > a > img`	www.mit.edu/files/images/202604/artemis-ii-launch-nasa-00_dw.jpg	44.7 KiB	6.0 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-0-IMG

nodeLabel: A cartoon cereal box is called “Phyt-O’s: the phytoplankton of the future” and …

path: 1,HTML,1,BODY,5,MAIN,2,DIV,0,DIV,0,ARTICLE,0,DIV,0,DIV,0,FIGURE,0,A,0,IMG

selector: div.spotlight__media > figure.spotlight__figure > a.spotlight__figure-link > img.spotlight__img

snippet: <img class="spotlight__img" src="/files/images/202604/MIT-PhytoFastFood-SL.jpg" alt="A cartoon cereal box is called “Phyt-O’s: the phytoplankton of the future”…">

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
www.mit.edu/	http/1.1
www.mit.edu/themes/mit/assets/css/main.css?t5zcu8	http/1.1
www.mit.edu/files/images/202604/MIT-PhytoFastFood-SL.jpg	http/1.1
www.mit.edu/themes/mit/assets/js/modernizr.js?t5zcu8	http/1.1
www.mit.edu/themes/mit/assets/js/main.js?t5zcu8	http/1.1
www.mit.edu/themes/mit/assets/favicon/manifest.webmanifest	http/1.1
www.mit.edu/files/images/202604/artemis-ii-launch-nasa-00_dw.jpg	http/1.1
www.mit.edu/files/images/202604/MIT-Insulin-Implant-SLdw.jpg	http/1.1
www.mit.edu/files/images/202603/MIT_battery-dendrites-home.jpg	http/1.1
www.mit.edu/files/images/202603/MIT-Hand-Tracker-SLsub.jpg	http/1.1
www.mit.edu/files/images/202505/Final-Thumbnails-Filehm.jpg	http/1.1
www.mit.edu/files/images/202505/MIT-This-is-MIT-SLsub_0_0.jpg	http/1.1
www.mit.edu/spotlights-export/suggested-links/?_format=json	http/1.1
/themes/mit/assets/js/SpotlightsExploreMoreLink.24ae33fb1...	http/1.1
www.mit.edu/themes/mit/assets/js/SpotlightsRecent.d6a3aa4b97b1659f1bbb.js	http/1.1
www.mit.edu/themes/mit/assets/js/Notification.11fc703b491d61aecf97.js	http/1.1
www.mit.edu/spotlights-export/recent/?_format=json	http/1.1
www.mit.edu/spotlights-export/announcements/?_format=json	http/1.1
www.mit.edu/themes/mit/assets/favicon/favicon.svg	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
www.mit.edu/themes/mit/assets/css/main.css?t5zcu8	75.1 KiB	937 ms
/p.css?s=1&k=uby1wjv&ht=tk&f=39496.39497.39498.39499.3950...	172 B	860 ms
use.typekit.net/uby1wjv.css	1.4 KiB	868 ms

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

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
EAPS scientists found that as sea surface temperatures rise, phytoplankton in p… `div#main > div.spotlight__width > article.spotlight > div.spotlight-inner`	0.181
EAPS scientists found that as sea surface temperatures rise, phytoplankton in p… `div#main > div.spotlight__width > article.spotlight > div.spotlight-inner`	0.027

The maximum potential First Input Delay that your users could experience is the duration of the longest task. Learn more about the Maximum Potential First Input Delay metric.

Why this matters

Performance issues directly impact user engagement and conversion rates.

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

Diagnostics

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: 540 ms 69.0 KiB

URL	Transfer Size	Est Savings
www.mit.edu/themes/mit/assets/css/main.css?t5zcu8	74.6 KiB	69.0 KiB

Reduce unused JavaScript and defer loading scripts until they are required to decrease bytes consumed by network activity. Learn how to reduce unused JavaScript.

Why this matters

Performance issues directly impact user engagement and conversion rates.

Estimated savings: 0.0 ms 250.7 KiB

URL	Transfer Size	Est Savings
www.mit.edu/themes/mit/assets/js/main.js?t5zcu8	366.6 KiB	184.4 KiB
www.googletagmanager.com/gtm.js?id=GTM-M8MGV4P	117.0 KiB	66.3 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
A cartoon cereal box is called “Phyt-O’s: the phytoplankton of the future” and … `div.spotlight__media > figure.spotlight__figure > a.spotlight__figure-link > img.spotlight__img`	www.mit.edu/files/images/202604/MIT-PhytoFastFood-SL.jpg

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

●Document request latency

●Optimize DOM size

●Forced reflow

●LCP breakdown

●Optimize viewport for mobile

●Minify CSS

●Minify JavaScript

●Avoids enormous network payloads Total size was 1,433 KiB

●JavaScript execution time 0.6 s

●Minimizes main-thread work 1.6 s

●Avoid long main-thread tasks 6 long tasks found

●Page didn't prevent back/forward cache restoration

●Network Requests

●Network Round Trip Times 40 ms

●Server Backend Latencies 400 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 460 ms

○INP breakdown

○User Timing marks and measures

○Avoid non-composited animations

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
div.es-search__width > form#es-search-form > div.es-search__box-mod > input#es-search-form-input `div.es-search__width > form#es-search-form > div.es-search__box-mod > input#es-search-form-input`

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.

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
Apr 4, 2026 `article.spotlight > div.spotlight-inner > div.spotlight__meta > h4.spotlight__date`

These are opportunities to improve keyboard navigation in your application.

Best practices

Touch targets with sufficient size and spacing help users who may have difficulty targeting small controls to activate the targets. Learn more about touch targets.

Why this matters

Performance issues directly impact user engagement and conversion rates.

Failing Elements
77 Massachusetts Avenue, Cambridge, MA, USA `footer.site-footer > div.site-footer__utility-mod > div.site-footer__contact-info > a.site-footer__contact-info-link`
Visit `div.site-footer__utility-mod > ul.site-footer__utility-list > li.site-footer__utility-item > a.site-footer__utility__text-link`
Events `div.site-footer__utility-mod > ul.site-footer__utility-list > li.site-footer__utility-item > a.site-footer__utility__text-link`
Jobs `div.site-footer__utility-mod > ul.site-footer__utility-list > li.site-footer__utility-item > a.site-footer__utility__text-link`
Privacy `div.site-footer__utility-mod > ul.site-footer__utility-list > li.site-footer__utility-item > a.site-footer__utility__text-link`
Accessibility `div.site-footer__utility-mod > ul.site-footer__utility-list > li.site-footer__utility-item > a.site-footer__utility__text-link`
Social Media Hub `li.site-footer__utility-item > ul.site-footer__social-list > li.site-footer__social-item > a.site-footer__social-item--connect-link`

These items highlight common accessibility best practices.

○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

●Buttons have an accessible name

●Image elements have `[alt]` attributes

●Form elements have associated labels

●`[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

●Background and foreground colors have a sufficient contrast ratio

●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.

●Links have a discernible name

●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

●Document has a main landmark.

●Deprecated ARIA roles were not used

○`[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

○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.

○Identical links have the same purpose.

○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.

100

Best Practices

●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 browser errors logged to the console

●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

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.

Content Best Practices

Meta descriptions may be included in search results to concisely summarize page content. Learn more about the meta description.

Why this matters

Performance issues directly impact user engagement and conversion rates.

Format your HTML in a way that enables crawlers to better understand your app’s content.

○Structured data is valid

●Page isn’t blocked from indexing

●Document has a `<title>` element

●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`