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Remove dead rules from stylesheets and defer the loading of CSS not used for above-the-fold content to reduce unnecessary bytes consumed by network activity. Learn more.

Resources are blocking the first paint of your page. Consider delivering critical JS/CSS inline and deferring all non-critical JS/styles. Learn more.

Redirects introduce additional delays before the page can be loaded. Learn more.

Remove unused JavaScript to reduce bytes consumed by network activity. Learn more.

Keep the server response time for the main document short because all other requests depend on it. Learn more.

Consider lazy-loading offscreen and hidden images after all critical resources have finished loading to lower time to interactive. Learn more.

Image formats like JPEG 2000, JPEG XR, and WebP often provide better compression than PNG or JPEG, which means faster downloads and less data consumption. Learn more.

Consider marking your touch and wheel event listeners as `passive` to improve your page's scroll performance. Learn more.

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

Consider reducing the time spent parsing, compiling and executing JS. You may find delivering smaller JS payloads helps with this. Learn more

Lists the longest tasks on the main thread, useful for identifying worst contributors to input delay. Learn more

This is the largest contentful element painted within the viewport. Learn More

The Critical Request Chains below show you what resources are loaded with a high priority. Consider reducing the length of chains, reducing the download size of resources, or deferring the download of unnecessary resources to improve page load. Learn more.

To set budgets for the quantity and size of page resources, add a budget.json file. Learn more.

Search engines may use `href` attributes on links to crawl websites. Ensure that the `href` attribute of anchor elements links to an appropriate destination, so more pages of the site can be discovered. Learn More

Informative elements should aim for short, descriptive alternate text. Decorative elements can be ignored with an empty alt attribute. Learn more.

Interactive elements like buttons and links should be large enough (48x48px), and have enough space around them, to be easy enough to tap without overlapping onto other elements. Learn more.

Image natural dimensions should be proportional to the display size and the pixel ratio to maximize image clarity. Learn more.

Specifying a doctype prevents the browser from switching to quirks-mode. Learn more. Expected publicId to be an empty string

All sites should be protected with HTTPS, even ones that don't handle sensitive data. This includes avoiding mixed content, where some resources are loaded over HTTP despite the initial request being servedover HTTPS. HTTPS prevents intruders from tampering with or passively listening in on the communications between your app and your users, and is a prerequisite for HTTP/2 and many new web platform APIs. Learn more.

If you're building a Progressive Web App, consider using a service worker so that your app can work offline. Learn more.

A service worker enables your web app to be reliable in unpredictable network conditions. Learn more. The start_url did respond, but not via a service worker.

A maskable icon ensures that the image fills the entire shape without being letterboxed when installing the app on a device. Learn more.

The browser address bar can be themed to match your site. Learn more. Failures: Manifest does not have `theme_color`.

For ideal appearance on iOS when users add a progressive web app to the home screen, define an `apple-touch-icon`. It must point to a non-transparent 192px (or 180px) square PNG. Learn More.

A themed splash screen ensures a high-quality experience when users launch your app from their homescreens. Learn more. Failures: Manifest does not have a PNG icon of at least 512px, Manifest does not have `background_color`, Manifest does not have `theme_color`.

The service worker is the technology that enables your app to use many Progressive Web App features, such as offline, add to homescreen, and push notifications. Learn more.

All sites should be protected with HTTPS, even ones that don't handle sensitive data. This includes avoiding mixed content, where some resources are loaded over HTTP despite the initial request being servedover HTTPS. HTTPS prevents intruders from tampering with or passively listening in on the communications between your app and your users, and is a prerequisite for HTTP/2 and many new web platform APIs. Learn more.

Disabling zooming is problematic for users with low vision who rely on screen magnification to properly see the contents of a web page. Learn more.

Assistive technologies, like screen readers, can't interpret ARIA attributes with invalid values. Learn more.

Each ARIA `role` supports a specific subset of `aria-*` attributes. Mismatching these invalidates the `aria-*` attributes. Learn more.

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

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 more.

Informative elements should aim for short, descriptive alternate text. Decorative elements can be ignored with an empty alt attribute. Learn more.

Form fields with multiple labels can be confusingly announced by assistive technologies like screen readers which use either the first, the last, or all of the labels. Learn more.

Low-contrast text is difficult or impossible for many users to read. Learn more.

Screen readers have a specific way of announcing lists. Ensuring proper list structure aids screen reader output. Learn more.

Screen readers require list items (`<li>`) to be contained within a parent `<ul>` or `<ol>` to be announced properly. Learn more.

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.