Apple releases Safari 26.3 browser: enhances Vision Pro immersive experience, supports Zstd to enable instant webpage loading on iPhone 17 and other devices

IT Home, February 12 — Technology media 9to5Mac today (February 12) published a blog post reporting that alongside the release of iOS / iPadOS 26.3 official version, Apple also simultaneously updated the Safari 26.3 browser. In addition to optimizing underlying performance, this update also upgrades the Vision Pro headset experience.

For users of visionOS 26.3, Safari now features automatic ambient light adjustment: when a web video enters full-screen mode, the browser will automatically dim the surrounding environment. Apple states that this change reduces visual distraction, helping users focus entirely on the video content.

In terms of performance, Safari 26.3 adds support for the Zstandard (Zstd) compression algorithm. IT Home notes: this is an open-source real-time compression algorithm developed by Meta (Facebook), capable of maintaining high compression ratios while providing extremely fast compression and decompression speeds, suitable for network data transmission, reducing bandwidth usage, and improving load times.

Apple points out that Zstd decompression is fast and can effectively reduce the processing load on user devices. Unlike the Brotli algorithm, which typically requires pre-compression during build processes, Zstd supports real-time compression, offering greater flexibility. However, users need to ensure their devices are running iOS 26.3, iPadOS 26.3, visionOS 26.3, or macOS Tahoe 26.3 to enjoy this feature.

For developers, Safari 26.3 improves the Navigation API. The new version exposes AbortSignal on NavigateEvent, which triggers when navigation is aborted. Apple emphasizes that this approach helps optimize resource management for web applications and provides a reliable way to cancel ongoing work after navigation interruptions.

Regarding bug fixes, IT Home quotes the blog post to list the following fixes in Safari 26.3:

• Fixed a position-try style parsing loop issue.
• Fixed an issue where elements at anchor points repeatedly switch from display: block to display: none during animations, causing position jumps.
• Fixed an issue where text-box-trim applied to root inline boxes caused underlines to render too high.
• Fixed an issue where applying widows and text-indent properties caused incorrect indentation in parts of paragraphs flowing into the next column.
• Fixed incorrect display of cursor styles such as move, scroll, ew-resize, and ns-resize.
• Fixed DOM timestamp handling errors by using raw touch timestamps.
• Extended glow effects to all button.circle elements, resolving the issue where full-screen buttons in inline video controls within visionOS could not be intuitively interacted with.
• Fixed a bug where Safari could not play live videos after removing and re-adding sourceBuffer content, causing seeking to fail.
• Fixed an issue where elements containing HDR JPEG and gain maps for positioning or transformation were incorrectly rendered as SDR.