Firefox 153 Lands with HDR Video, Deeper Web-Compatibility Tricks, and a New Local Testing Mode

Mozilla has shipped Firefox 153 to the stable release channel, and while it doesn’t come wrapped in a flashy redesign, it quietly closes several long-standing gaps between Firefox and the rest of the browser field. HDR video finally works properly on Windows, a chunk of the non-standard scrollbar styling that web developers have leaned on for years now renders correctly, and a new “Local Mode” setting removes one of the most annoying friction points in front-end testing. Here’s everything that changed, why it matters, and what’s already brewing for the next release.

The Headline Feature: HDR Video Playback on Windows

For years, Firefox users on Windows watched high-dynamic-range video the same way everyone else did before HDR support existed: flattened, washed out, and noticeably duller than the same clip played in a Chromium-based browser. Firefox 153 changes that. HDR video playback is now available on Windows, provided HDR mode is switched on for the display through Windows Settings, under Display.

It’s a meaningful upgrade for anyone who streams video content professionally graded for HDR, whether that’s a nature documentary, a modern film release, or footage shot on a phone that supports the format. The catch, and it’s worth knowing before you get excited, is that support is not universal yet. Laptop displays that only advertise “HDR video streaming” rather than full local HDR are not supported in this release, and some videos recorded on phones in particular orientations are not currently detected as HDR content. Mozilla has been upfront that this is a first pass rather than a finished feature, so expect refinements in the point releases that follow.

Still, for the mainstream case of a desktop or laptop with a properly HDR-capable panel, this closes a gap that has quietly pushed video-heavy users toward other browsers. It is one of those changes that will not show up in a screenshot, but will be immediately obvious the first time someone plays back a properly mastered HDR clip.

Scrollbars Get a Compatibility Patch

The second major change in Firefox 153 is more of an engineering curiosity, but it solves a real headache for web developers. Firefox now supports a limited subset of the non-standard ::-webkit-scrollbar pseudo-element, which for over a decade has been the de facto way that sites style scrollbars in WebKit and Chromium browsers. Firefox never implemented it, which meant sites either had ugly, unstyled scrollbars in Firefox or developers had to maintain separate CSS just to patch around the gap.

The new implementation is intentionally narrow. A few of the practical behaviors now supported include:

• Rules that set a non-zero width or height on the pseudo-element now disable overlay scrollbars for that container, matching what happens in Chromium browsers.
• display: none applied to ::-webkit-scrollbar behaves like the standard scrollbar-width: none property, hiding the scrollbar entirely.
• Feature queries using @supports selector(::-webkit-scrollbar) now correctly evaluate to true, so sites that branch their CSS based on browser capability will detect Firefox properly.

Full styling, meaning custom scrollbar colors, thumb shapes, and border-radius values, is deliberately left out for now. Mozilla’s own release notes frame this as a compatibility patch rather than a new styling API, and the standards-track scrollbar-color and scrollbar-width properties remain the “correct” way to style scrollbars going forward. But for the enormous volume of existing sites that only wrote webkit-prefixed scrollbar rules and never tested in Firefox, this quietly fixes broken-looking pages without anyone touching a line of code.

A Small but Useful Developer Tools Addition: Local Mode

Buried in the options panel of Firefox’s developer tools is a new setting that solves a problem nearly every front-end developer has run into: testing APIs that refuse to work over a plain file:// URL. Browsers have historically blocked certain web platform features, like service workers, module scripts, and various storage APIs, from running against files opened directly from disk, for good security reasons. The usual workaround has been spinning up a throwaway local web server just to get around the restriction.

Firefox 153’s new “Local Mode” setting allows developers to load local directories as custom origins directly from the browser, sidestepping the need for a server entirely for many testing scenarios. It also supports mapping multiple local directories at once, which is handy for anyone testing a multi-package project or comparing behavior across different builds side by side. It is a small quality-of-life change, but it is the kind of thing that saves five minutes dozens of times a week, which adds up fast for anyone doing serious front-end work.

What Changed Under the Hood for Enterprise Users

Organizations running managed Firefox deployments should check the dedicated Firefox for Enterprise 153 release notes, which cover policy updates and enterprise-specific bug fixes separate from the consumer changelog. As always with a major version bump, IT administrators pushing Firefox through group policy or MDM tools will want to validate their configuration profiles before wide rollout, particularly if any policies interact with scrollbar rendering or media playback settings.

Platforms Firefox Has Left Behind

Firefox 153 also marks the end of the road for a couple of older platforms. The browser is no longer supported on Windows 8.1 and earlier, and no longer supported on macOS 10.14 (Mojave) and earlier. Anyone still running those operating systems will need to switch to Firefox ESR, the Extended Support Release channel, which continues to receive security patches on a slower, more conservative cadence without the churn of feature updates. This is a fairly standard move for Mozilla, which periodically trims platform support to keep the core codebase from being weighed down by increasingly rare configurations, but it is worth flagging for anyone managing a fleet of older machines.

Already Looking Ahead: Firefox 154 in Beta

With 153 out the door, Mozilla has already promoted Firefox 154 to the public beta channel, giving an early look at what is coming next. Firefox 154 is scheduled to ship on August 18, 2026, alongside parallel updates to the 153.2, 140.15, and 115.40.0 ESR branches. A few of the highlights developers and testers are already poking at include:

• A new “Manage AI” quick action in the address bar that jumps straight to the AI section of Firefox’s settings.
• The ability to highlight selected text inside PDFs the same way you would on a normal web page, closing a gap between Firefox’s built-in PDF viewer and dedicated PDF readers.
• Support for clearing and refreshing cached favicons on a hard reload, so a site’s icon updates immediately instead of showing a stale version.
• An updated JSON Viewer with a breadcrumb path at the bottom showing exactly where the currently selected entry sits in the document tree.
• Support for Iterator.prototype.includes(), a small but genuinely useful JavaScript addition that lets developers check whether an iterator contains a given value without first converting it into an array.

Because it is still in beta, none of this is final, and Mozilla explicitly warns against using beta builds for production work. But the roadmap gives a reasonable preview of where the browser is headed over the next several weeks.

Editor’s take: neither HDR playback nor a partial scrollbar polyfill is the kind of feature that generates headlines, but both are the sort of unglamorous plumbing work that determines whether a browser feels “finished” next to its competitors. Firefox has spent the last several releases chipping away at exactly this category of gap, and 153 is a solid, if quiet, entry in that pattern.

How Firefox 153 Stacks Up Against the Competition

It is worth putting these changes in context. Chromium-based browsers, including Chrome and Edge, have supported some form of HDR video for several release cycles now, and the webkit-prefixed scrollbar styling that Firefox is only now partially adopting has been a Chromium and Safari staple for well over a decade. Seen that way, Firefox 153 is less about leapfrogging the competition and more about closing a gap that has quietly nudged some users and developers toward other browsers by default. That framing matters because it changes what success looks like for this release. Nobody should expect headlines proclaiming Firefox has “caught up” to Chrome, because the changes are narrow and, in the case of scrollbars, deliberately incomplete. What they should expect is a slightly less annoying day-to-day experience: video that finally looks right, and websites that finally render the way their developers intended, without either side having done anything differently.

There is also a broader strategic angle here. Firefox has spent the better part of the last two years focused heavily on compatibility work, adopting non-standard behaviors from competing engines specifically because so much of the modern web was authored and tested against Chromium first. That is not a flattering position for an independent browser engine to be in, but it is a pragmatic one, and Mozilla has been fairly transparent about the trade-off in its own developer communications. Prioritizing compatibility patches over exotic new capabilities keeps existing sites working correctly today, even if it means Firefox spends more of its engineering budget playing catch-up on de facto standards than pioneering entirely new ones.

What Site Owners and Developers Should Actually Do

For developers maintaining production sites, the practical takeaway from the scrollbar change is straightforward: existing webkit-prefixed scrollbar CSS will now behave more consistently in Firefox without any code changes required, but it remains worth testing rather than assuming. Because Firefox’s implementation is intentionally a subset rather than a full match, any site relying on advanced scrollbar customization, particularly colored thumbs, custom border radii, or multi-part styling, will still see gaps compared to Chromium. Teams that maintain a Firefox-specific stylesheet fallback should hold onto it for now rather than deleting it immediately after this release, since the two rendering paths are converging but have not fully merged.

For anyone building or maintaining local development tooling, the new Local Mode setting is worth adopting even for teams that already run a local server for testing, simply because it removes an entire category of “did I forget to start the server” friction from a workflow. It is a small thing, but small things compound across a team working the same routines dozens of times a day.

Frequently Asked Questions

Do I need to change any settings to get HDR video working?

Yes. HDR mode needs to be explicitly enabled for your display through Windows Settings, under Display, in addition to updating to Firefox 153. The browser update alone is not sufficient if HDR is not already turned on at the operating system level.

Will my extensions still work after updating?

In general, yes. Firefox’s extension platform has remained fairly stable across recent major versions, and most well-maintained extensions continue to function normally through version bumps like this one. It is still good practice to check for extension updates around the time of a major browser release, since developers sometimes ship compatibility patches alongside a new Firefox version.

Is Firefox 154 safe to install now?

Not for daily use. It is currently in the beta channel specifically for testing purposes, and Mozilla explicitly recommends against relying on beta builds for production or otherwise important work. Wait for the stable release on August 18, 2026, unless you specifically want to help test upcoming features and are comfortable with the occasional rough edge.

How to Get It

Firefox 153 is rolling out now through the browser’s built-in update mechanism, and is also available as a fresh download from Mozilla’s official site for Windows, macOS, and Linux. As with any major browser update, it is worth backing up your bookmarks and checking that any critical extensions have been updated for compatibility before you update production machines, though Firefox’s extension ecosystem has historically weathered version bumps well.

For teams managing multiple installations, the Firefox for Enterprise release notes remain the best starting point for policy-level detail, while individual users can simply let the browser update itself in the background, as it does by default on most configurations.