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.scala-lang.org/resources/img/frontpage/notebook.png	14400.0 s	190.9 KiB
www.scala-lang.org/resources/js/vendor/codemirror/codemirror.js	14400.0 s	94.3 KiB
www.scala-lang.org/resources/img/frontpage/scala-spiral.png	14400.0 s	78.6 KiB
www.scala-lang.org/resources/glyphs/Inconsolata_SemiExpanded-SemiBold.ttf	14400.0 s	50.7 KiB
www.scala-lang.org/resources/img/frontpage/gradle-logo.png	14400.0 s	17.5 KiB
www.scala-lang.org/resources/img/frontpage/epfl-logo.png	14400.0 s	15.9 KiB
www.scala-lang.org/resources/css/style.css?v=20260407174504	14400.0 s	15.4 KiB
www.scala-lang.org/resources/img/frontpage/scalacenter-logo.png	14400.0 s	11.2 KiB
www.scala-lang.org/resources/img/frontpage/jetbrains-logo.png	14400.0 s	10.6 KiB
www.scala-lang.org/resources/js/vendor/codemirror/clike.js	14400.0 s	8.3 KiB
www.scala-lang.org/resources/js/vendor/jquery.autocomplete.js	14400.0 s	7.2 KiB
www.scala-lang.org/resources/js/vendor/unslider.js	14400.0 s	6.7 KiB
www.scala-lang.org/resources/js/functions.js?v=20260407174504	14400.0 s	6.7 KiB
www.scala-lang.org/resources/js/vendor/prettify/prettify.js	14400.0 s	6.2 KiB
www.scala-lang.org/resources/img/frontpage/llvm-logo.png	14400.0 s	5.6 KiB
www.scala-lang.org/resources/img/frontpage/virtuslab-logo.png	14400.0 s	5.4 KiB
www.scala-lang.org/resources/img/frontpage/scala-logo-white@2x.png	14400.0 s	5.4 KiB
www.scala-lang.org/resources/img/frontpage/scaladex-logo.png	14400.0 s	5.1 KiB
www.scala-lang.org/resources/img/frontpage/company-logo.png	14400.0 s	4.8 KiB
www.scala-lang.org/resources/js/tweetMachine-update.js	14400.0 s	4.7 KiB
www.scala-lang.org/resources/img/frontpage/akka-logo.png	14400.0 s	4.7 KiB
www.scala-lang.org/resources/img/frontpage/java-logo.png	14400.0 s	4.2 KiB
www.scala-lang.org/resources/js/hljs-scala3.js	14400.0 s	3.7 KiB
www.scala-lang.org/resources/css/vendor/codemirror.css	14400.0 s	2.8 KiB
www.scala-lang.org/resources/img/frontpage/scala-logo-white.png	14400.0 s	2.6 KiB
www.scala-lang.org/resources/img/frontpage/js-logo.png	14400.0 s	2.4 KiB
www.scala-lang.org/resources/js/vendor/jekyll.search.min.js	14400.0 s	2.2 KiB
www.scala-lang.org/resources/css/highlightjs-dark.css	14400.0 s	1.8 KiB
www.scala-lang.org/resources/img/icons/icon5.svg	14400.0 s	1.8 KiB
www.scala-lang.org/resources/img/icons/icon4.svg	14400.0 s	1.7 KiB
www.scala-lang.org/resources/img/icons/icon8.svg	14400.0 s	1.6 KiB
www.scala-lang.org/resources/img/icons/icon7.svg	14400.0 s	1.4 KiB
www.scala-lang.org/resources/img/icons/icon11.svg	14400.0 s	1.4 KiB
www.scala-lang.org/resources/img/scala-logo-large.svg	14400.0 s	1.2 KiB
www.scala-lang.org/resources/js/vendor/prettify/lang-scala.js	14400.0 s	913 B
www.scala-lang.org/resources/css/vendor/monokai.css	14400.0 s	835 B
www.scala-lang.org/resources/css/unslider-dots.css	14400.0 s	756 B
www.scala-lang.org/resources/css/unslider.css	14400.0 s	590 B
www.scala-lang.org/resources/css/monospace.css	14400.0 s	492 B

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
cdnjs.cloudflare.com/ajax/libs/font-awesome/6.5.2/webfonts/fa-solid-900.woff2	25 ms
www.scala-lang.org/resources/glyphs/Inconsolata_SemiExpanded-SemiBold.ttf	20 ms
fonts.gstatic.com/s/robotoslab/v36/BngMUXZYTXPIvIBgJJSb6ufN5qWr4xCC.woff2	20 ms
fonts.gstatic.com/s/caveat/v23/WnznHAc5bAfYB2QRah7pcpNvOx-pjfJ9eIWpYT5Mmgo.woff2	20 ms
fonts.gstatic.com/s/lato/v25/S6u9w4BMUTPHh50XSwiPGQ3q5d0.woff2	15 ms
fonts.gstatic.com/s/lato/v25/S6uyw4BMUTPHjx4wXiWtFCc.woff2	15 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:Source valueType:source-location] map[granularity:1 key:reflowTime label:Total reflow time valueType:ms]]

items: [map[reflowTime:58.546 source:map[column:599 line:0 type:source-location url:https://plausible.scala-lang.org/js/script.js 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.resources > div.scala-brand-circle > div.circle-solid > img `div.resources > div.scala-brand-circle > div.circle-solid > img`	www.scala-lang.org/resources/img/frontpage/scala-spiral.png	78.1 KiB	74.3 KiB
Gradle `div.wrap > div.supported > a > img.logo-with-wider-aspect-ratio`	www.scala-lang.org/resources/img/frontpage/gradle-logo.png	17.1 KiB	16.4 KiB
EPFL `div.wrap > div.supported > a > img`	www.scala-lang.org/resources/img/frontpage/epfl-logo.png	15.6 KiB	15.6 KiB
Scala Center `ul.maintained > li > a > img`	www.scala-lang.org/resources/img/frontpage/scalacenter-logo.png	10.9 KiB	9.5 KiB
JetBrains `div.wrap > div.supported > a > img.logo-with-wider-aspect-ratio`	www.scala-lang.org/resources/img/frontpage/jetbrains-logo.png	10.3 KiB	9.3 KiB
div.browser > div.header-browser > a > img `div.browser > div.header-browser > a > img`	www.scala-lang.org/resources/img/frontpage/scaladex-logo.png	4.8 KiB	4.7 KiB
VirtusLab `ul.maintained > li > a > img`	www.scala-lang.org/resources/img/frontpage/virtuslab-logo.png	5.1 KiB	4.3 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-7-SECTION

nodeLabel: Get tickets Bringing Scala Days in... 12-13 October 2026 at Kulturbrauerei, Ber…

path: 1,HTML,1,BODY,0,SECTION

selector: body > section#countdown-clock-2025

snippet: <section id="countdown-clock-2025" class="scala-days-countdown">

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

value: No additional origins are good candidates for preconnecting

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.scala-lang.org/resources/css/highlightjs-dark.css	1.8 KiB
ajax.googleapis.com/ajax/libs/jquery/3.1.1/jquery.min.js	30.2 KiB	1.2 s
fonts.googleapis.com/css?family=Lato:300,400,400i,700i,900	590 B	780 ms
fonts.googleapis.com/css?family=Caveat	582 B
fonts.googleapis.com/css?family=Roboto+Slab:400,700	767 B	151 ms
fonts.googleapis.com/css?family=Kalam:300,400,700	989 B
cdnjs.cloudflare.com/ajax/libs/font-awesome/6.5.2/css/all.min.css	19.1 KiB	1.1 s
www.scala-lang.org/resources/css/vendor/codemirror.css	2.8 KiB	152 ms
www.scala-lang.org/resources/css/unslider-dots.css	756 B	152 ms
www.scala-lang.org/resources/css/style.css?v=20260407174504	15.4 KiB	152 ms
www.scala-lang.org/resources/css/monospace.css	492 B
www.scala-lang.org/resources/css/vendor/monokai.css	835 B
www.scala-lang.org/resources/css/unslider.css	590 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

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.

Diagnostics

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: 150 ms 46.0 KiB

URL	Transfer Size	Est Savings
www.scala-lang.org/resources/js/vendor/codemirror/codemirror.js	94.0 KiB	31.3 KiB
www.scala-lang.org/resources/js/vendor/unslider.js	6.4 KiB	3.9 KiB
www.scala-lang.org/resources/js/vendor/jquery.autocomplete.js	6.9 KiB	3.2 KiB
www.scala-lang.org/resources/js/tweetMachine-update.js	4.4 KiB	3.1 KiB
www.scala-lang.org/resources/js/functions.js?v=20260407174504	6.4 KiB	2.6 KiB
www.scala-lang.org/resources/js/vendor/codemirror/clike.js	8.0 KiB	2.0 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: 450 ms 29.1 KiB

URL	Transfer Size	Est Savings
cdnjs.cloudflare.com/ajax/libs/font-awesome/6.5.2/css/all.min.css	18.5 KiB	18.3 KiB
www.scala-lang.org/resources/css/style.css?v=20260407174504	15.0 KiB	10.8 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: 370 ms 78.4 KiB

URL	Transfer Size	Est Savings
www.scala-lang.org/resources/js/vendor/codemirror/codemirror.js	94.0 KiB	78.4 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
EPFL `div.wrap > div.supported > a > img`	www.scala-lang.org/resources/img/frontpage/epfl-logo.png
div.resources > div.scala-brand-circle > div.circle-solid > img `div.resources > div.scala-brand-circle > div.circle-solid > img`	www.scala-lang.org/resources/img/frontpage/scala-spiral.png
Gradle `div.wrap > div.supported > a > img.logo-with-wider-aspect-ratio`	www.scala-lang.org/resources/img/frontpage/gradle-logo.png
Scala Center `ul.maintained > li > a > img`	www.scala-lang.org/resources/img/frontpage/scalacenter-logo.png
VirtusLab `ul.maintained > li > a > img`	www.scala-lang.org/resources/img/frontpage/virtuslab-logo.png
Akka `ul.maintained > li > a > img`	www.scala-lang.org/resources/img/frontpage/akka-logo.png
Your company `div.wrap > div.supported > a > img`	www.scala-lang.org/resources/img/frontpage/company-logo.png
div.browser > div.header-browser > a > img `div.browser > div.header-browser > a > img`	www.scala-lang.org/resources/img/frontpage/scaladex-logo.png
JetBrains `div.wrap > div.supported > a > img.logo-with-wider-aspect-ratio`	www.scala-lang.org/resources/img/frontpage/jetbrains-logo.png
footer#site-footer > div.wrap > div.site-footer-bottom > img `footer#site-footer > div.wrap > div.site-footer-bottom > img`	www.scala-lang.org/resources/img/frontpage/scala-logo-white.png

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

●Layout shift culprits

●Document request latency

●Optimize DOM size

●LCP breakdown

●Modern HTTP

●Optimize viewport for mobile

●Minify CSS

●Avoids enormous network payloads Total size was 959 KiB

●JavaScript execution time 0.4 s

●Minimizes main-thread work 1.5 s

●Avoid long main-thread tasks 6 long tasks found

●Page didn't prevent back/forward cache restoration

●Network Requests

●Network Round Trip Times 10 ms

●Server Backend Latencies 290 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 300 ms

○INP breakdown

○User Timing marks and measures

○Avoid non-composited animations

○Avoid large layout shifts

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

Some ARIA parent roles must contain specific child roles to perform their intended accessibility functions. Learn more about roles and required children elements.

Why this matters

Performance issues directly impact user engagement and conversion rates.

Failing Elements
LEARN INSTALL PLAYGROUND FIND A LIBRARY COMMUNITY GOVERNANCE BLOG `header#site-header > div.header-background > div.wrap > nav.navigation`

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.

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
older releases, including Scala 2 `div.col-lg-6 > div.inner-text > p > a`
// prints: with 'a' × 1 = List(apple) `div.highlight > pre.highlight > code.hljs > span.hljs-comment`
// prints: with 'a' × 2 = List(avocado) `div.highlight > pre.highlight > code.hljs > span.hljs-comment`
// prints: with 'a' × 3 = List(banana, papaya) `div.highlight > pre.highlight > code.hljs > span.hljs-comment`
GET STARTED `div.wrap > div.resources > div.get-started > a.button`
DOCUMENTATION `div.wrap > div.resources > div.learn-scala > a.button`

These are opportunities to improve the legibility of your content.

Internationalization and localization

If a page doesn't specify a `lang` attribute, a screen reader assumes that the page is in the default language that the user chose when setting up the screen reader. If the page isn't actually in the default language, then the screen reader might not announce the page's text correctly. Learn more about the `lang` attribute.

Why this matters

Performance issues directly impact user engagement and conversion rates.

Failing Elements
html `html`

These are opportunities to improve the interpretation of your content by users in different locales.

Names and labels

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.header-background > div.wrap > nav.navigation > a.navigation-band `div.header-background > div.wrap > nav.navigation > a.navigation-band`
div.wrap > div.browser > div.header-browser > a `div.wrap > div.browser > div.header-browser > a`

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.

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
Run in playground `section#collections-ops_content > div.code-element > div.dark > button.code-snippet-button`
Run in playground `div.code-element > div.dark > button.code-snippet-button > a`

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

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

●Document has a `<title>` element

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

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

●Heading elements appear in a sequentially-descending order

●Document has a main landmark.

●Deprecated ARIA roles were not used

●Identical links have the same purpose.

○`[accesskey]` values are unique

○`[aria-*]` attributes match their roles

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

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

○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 use only permitted ARIA attributes

○`[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

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

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

○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 a valid value for its `[lang]` attribute

○`<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

○Links are distinguishable without relying on color.

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

○`<object>` elements have alternate text

○Select elements have associated label elements.

○Skip links are focusable.

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

○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.

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 clickjacking with XFO or CSP

●Mitigate DOM-based XSS with Trusted Types

●Detected JavaScript libraries

●Page has valid source maps

○Redirects HTTP traffic to HTTPS

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`