New features in Safari on iOS 27 (released on 2026-09-14)

• alpha()

  Newly Available (since 2026-09-14)

  The alpha() CSS function computes a relative color value by adjusting the opacity of an origin color.

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  • Chrome 151 Released on 2026-07-28
  • Chrome Android 151 Released on 2026-07-28
  • Edge 151 Released on 2026-07-31
  • Firefox 155 Released on 2026-09-01
  • Firefox for Android 155 Released on 2026-09-01
  • Safari 27 Released on 2026-09-14
  • Safari on iOS 27 Released on 2026-09-14

• Anchor positioning

  Limited availability

  Anchor positioning places an element based on the position of another element. For example, you can place a tooltip next to the content it references.

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  • Chrome Not supported
  • Chrome Android Not supported
  • Edge Not supported
  • Firefox Not supported Position: positive
  • Firefox for Android Not supported Position: positive
  • Safari 27 Released on 2026-09-14
  • Safari on iOS 27 Released on 2026-09-14

• Anchor positioning transforms

  Limited availability

  Anchor positioned elements take CSS transforms on their anchor elements into account.

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  • Chrome 144 Released on 2026-01-13
  • Chrome Android 144 Released on 2026-01-13
  • Edge 144 Released on 2026-01-21
  • Firefox Not supported
  • Firefox for Android Not supported
  • Safari 27 Released on 2026-09-14
  • Safari on iOS 27 Released on 2026-09-14

  Baseline availability blocked since September 2026 by Firefox (1 months)

• ariaNotify()

  Newly Available (since 2026-09-14)

  The ariaNotify() method of Element and Document requests assistive technology software, if activated, to announce a message to the user. This can help make dynamic content changes more accessible to users.

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  • Chrome 141 Released on 2025-09-30
  • Chrome Android 141 Released on 2025-09-30
  • Edge 141 Released on 2025-10-03
  • Firefox 150 Released on 2026-04-21
  • Firefox for Android 150 Released on 2026-04-21
  • Safari 27 Released on 2026-09-14
  • Safari on iOS 27 Released on 2026-09-14

• Asynchronously iterable streams

  Newly Available (since 2026-09-14)

  Asynchronous iteration of a stream allows you to use for await … of loops to iterate through a stream's incoming data.

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  • Chrome 124 Released on 2024-04-16
  • Chrome Android 124 Released on 2024-04-16
  • Edge 124 Released on 2024-04-18
  • Firefox 110 Released on 2023-02-14
  • Firefox for Android 110 Released on 2023-02-14
  • Safari 27 Released on 2026-09-14
  • Safari on iOS 27 Released on 2026-09-14

• Case-sensitive attribute selector

  Limited availability

  The s identifier in a CSS attribute selector matches attribute values case-sensitively in document languages like HTML where attribute values are case-insensitive.

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  • Chrome Not supported
  • Chrome Android Not supported
  • Edge Not supported
  • Firefox 66 Released on 2019-03-19
  • Firefox for Android 66 Released on 2019-03-19
  • Safari 27 Released on 2026-09-14
  • Safari on iOS 27 Released on 2026-09-14

  Baseline availability blocked since September 2026 by Chromium (1 months)

• color-mix() with three or more colors

  Limited availability

  The color-mix() CSS function accepts three or more colors.

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  • Chrome Not supported
  • Chrome Android Not supported
  • Edge Not supported
  • Firefox 150 Released on 2026-04-21
  • Firefox for Android 150 Released on 2026-04-21
  • Safari 27 Released on 2026-09-14
  • Safari on iOS 27 Released on 2026-09-14

  Baseline availability blocked since September 2026 by Chromium (1 months)

• Customizable <select>

  Limited availability

  The <select> element's appearance, including the button, selected option, picker dropdown, and options, can be customized using CSS.

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  • Chrome 135 Released on 2025-04-01
  • Chrome Android 135 Released on 2025-04-01
  • Edge 135 Released on 2025-04-04
  • Firefox Not supported Position: positive
  • Firefox for Android Not supported Position: positive
  • Safari 27 Released on 2026-09-14
  • Safari on iOS 27 Released on 2026-09-14

  Baseline availability blocked since September 2026 by Firefox (1 months)

• light-dark() image values

  Newly Available (since 2026-09-14)

  The light-dark() CSS function accepts, in addition to colors, two <image> values, such as a gradient or URL, and uses one depending on the current color scheme.

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  • Chrome 150 Released on 2026-06-30
  • Chrome Android 150 Released on 2026-06-30
  • Edge 150 Released on 2026-07-02
  • Firefox 150 Released on 2026-04-21
  • Firefox for Android 150 Released on 2026-04-21
  • Safari 27 Released on 2026-09-14
  • Safari on iOS 27 Released on 2026-09-14

• overflow-anchor

  Newly Available (since 2026-09-14)

  The overflow-anchor CSS property sets an element as a possible scroll anchor, reducing unintended scrolling when document changes occur above the current scrollport. This is enabled by default where supported.

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  • Chrome 56 Released on 2017-01-25
  • Chrome Android 56 Released on 2017-02-01
  • Edge 79 Released on 2020-01-15
  • Firefox 66 Released on 2019-03-19
  • Firefox for Android 66 Released on 2019-03-19
  • Safari 27 Released on 2026-09-14
  • Safari on iOS 27 Released on 2026-09-14

• ReadableStream.from()

  Limited availability

  The ReadableStream.from() static method converts an iterable or async iterable object, such as an array or async generator function, into a readable stream.

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  • Chrome Not supported
  • Chrome Android Not supported
  • Edge Not supported
  • Firefox 117 Released on 2023-08-29
  • Firefox for Android 117 Released on 2023-08-29
  • Safari 27 Released on 2026-09-14
  • Safari on iOS 27 Released on 2026-09-14

  Baseline availability blocked since September 2026 by Chromium (1 months)

• Service workers static routing

  Limited availability

  The service worker install event's addRoutes method declares resource paths that should either be fetched from the network or the cache, to bypass the service worker and improve performance.

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  • Chrome 123 Released on 2024-03-19
  • Chrome Android 123 Released on 2024-03-19
  • Edge 123 Released on 2024-03-22
  • Firefox Not supported
  • Firefox for Android Not supported
  • Safari 27 Released on 2026-09-14
  • Safari on iOS 27 Released on 2026-09-14

  Baseline availability blocked since September 2026 by Firefox (1 months)

• stretch

  Limited availability

  The stretch CSS keyword expands a box as needed to fit its contents until the maximum size is reached, without preserving the content's preferred aspect ratio.

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  • Chrome 138 Released on 2025-06-24
  • Chrome Android 138 Released on 2025-06-24
  • Edge 138 Released on 2025-06-26
  • Firefox Not supported Position: positive
  • Firefox for Android Not supported Position: positive
  • Safari 27 Released on 2026-09-14
  • Safari on iOS 27 Released on 2026-09-14

  Baseline availability blocked since September 2026 by Firefox (1 months)

• text-autospace

  Limited availability

  The text-autospace CSS property sets whether and how to insert spaces in inter-script text (such as when mixing Latin and Chinese characters) and around punctuation.

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  • Chrome Not supported
  • Chrome Android Not supported
  • Edge Not supported
  • Firefox 145 Released on 2025-11-11
  • Firefox for Android 145 Released on 2025-11-11
  • Safari 27 Released on 2026-09-14
  • Safari on iOS 27 Released on 2026-09-14

  Baseline availability blocked since September 2026 by Chromium (1 months)

• Top-level await

  Newly Available (since 2026-09-14)

  The await keyword, when used at the top level of a module (outside of an async function), delays parent module execution until after a promise fulfills.

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  • Chrome 89 Released on 2021-03-02
  • Chrome Android 89 Released on 2021-03-02
  • Edge 89 Released on 2021-03-04
  • Firefox 89 Released on 2021-06-01
  • Firefox for Android 89 Released on 2021-06-01
  • Safari 27 Released on 2026-09-14
  • Safari on iOS 27 Released on 2026-09-14

• JavaScript promise integration (WebAssembly)

  Newly Available (since 2026-09-14)

  The JavaScript promise integration (JSPI) suspends a WebAssembly module when it calls a JavaScript method that returns a promise. The module resumes when the promise is resolved. You can use this to call asynchronous Web APIs from synchronous WebAssembly.

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  • Chrome 137 Released on 2025-05-27
  • Chrome Android 137 Released on 2025-05-27
  • Edge 137 Released on 2025-05-29
  • Firefox 153 Released on 2026-07-21
  • Firefox for Android 153 Released on 2026-07-21
  • Safari 27 Released on 2026-09-14
  • Safari on iOS 27 Released on 2026-09-14

• WebOTP

  Limited availability

  The OTPCredential API represents a one-time-password (OTP).

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  • Chrome 93 Released on 2021-08-31
  • Chrome Android 84 Released on 2020-07-27
  • Edge 93 Released on 2021-09-02
  • Firefox Not supported
  • Firefox for Android Not supported
  • Safari 27 Released on 2026-09-14
  • Safari on iOS 27 Released on 2026-09-14

  Baseline availability blocked since September 2026 by Firefox (1 months)