# Safari Technology Preview 66 Release Notes Preview the latest web technology updates including: Web Share API, Conic Gradients, WebRTC, Shadow DOM, CSS, Web Inspector, Web API, Apple Pay, JavaScript, Media, Web Animations, Web Assembly, and Password AutoFill. ## Overview [Safari Technology Preview](https://webkit.org/blog/6017/introducing-safari-technology-preview/) Release 66 is now [available for download](https://webkit.org/downloads/) for macOS Mojave and macOS High Sierra. If you already have Safari Technology Preview installed, you can update in the Software Update pane of System Preferences on macOS Mojave and from the Mac App Store’s Updates tab on macOS High Sierra. After updating to macOS Mojave, you may have to reinstall Safari Technology Preview. This release covers WebKit revisions [235669-236195](https://trac.webkit.org/log?stop_rev=235669&rev=236195&limit=999). This release of Safari Technology Preview has a known issue where launching SafariDriver fails. ### Web Share API - Implemented the Web Share API ([r235925](https://trac.webkit.org/changeset/235925/webkit/)) ### Conic Gradients - Added support for Conic Gradients ([r235772](https://trac.webkit.org/changeset/235772/webkit/)) - Fixed angle interpretation for Conic Gradients ([r235868](https://trac.webkit.org/changeset/235868/webkit/)) - Fixed color stop blending in Conic Gradients for stops past the first stop ([r235999](https://trac.webkit.org/changeset/235999/webkit/)) ### WebRTC - Enabled WebRTC Unified Plan as an Experimental Feature ([r236144](https://trac.webkit.org/changeset/236144/webkit/)) - Exposed `RTCRtpSender.setParameters` ([r235714](https://trac.webkit.org/changeset/235714/webkit/)) - Introduced a backend for RTCRtpTransceiver ([r235719](https://trac.webkit.org/changeset/235719/webkit/)) ### Shadow DOM - Fixed `:first-child`, `:last-child`, `:nth-child`, and `:nth-of-type` to work on shadow root’s children ([r235917](https://trac.webkit.org/changeset/235917/webkit/)) - Fixed `mouseenter` and `mouseleave` events to get dispatched when there is a capturing event listener for a slot ancestor ([r235865](https://trac.webkit.org/changeset/235865/webkit/)) ### CSS - Added support for double-position gradient color stop syntax ([r236155](https://trac.webkit.org/changeset/236155/webkit/)) ### Web Inspector - Updated the bezier curve editor for Dark Mode ([r235998](https://trac.webkit.org/changeset/235998/webkit/)) - Changed to generate CSSKeywordCompletions from backend values ([r236091](https://trac.webkit.org/changeset/236091/webkit/)) - Fixed imported recordings that are unable to be viewed after navigation ([r235937](https://trac.webkit.org/changeset/235937/webkit/)) - Fixed opening Web Inspector with a selected element that might immediately scroll that element off screen in the DOM Tree outline ([r235996](https://trac.webkit.org/changeset/235996/webkit/)) - Changed to record actions performed on ImageBitmapRenderingContext ([r236008](https://trac.webkit.org/changeset/236008/webkit/)) - Fixed Source View to scroll to show the line when a breakpoint is hit inside of a `