Summary & Key Takeaways ​

• Safari 26.5 adds the :open pseudo-class, allowing styling of elements that are in an "open" state, such as <details> or <dialog>.
• The element-scoped keyword is introduced for the random() CSS function, enabling scoped random values.
• Support for color-interpolation is added for SVG gradients, enhancing control over color transitions.
• The ToggleEvent.source property is now available for popovers, providing information about what triggered a popover's toggle.
• The Origin API is also included, offering new capabilities for managing web origins.

Our Commentary ​

It's always good to see WebKit pushing forward with new web platform features. The :open pseudo-class is a welcome addition for more declarative styling of interactive elements, and ToggleEvent.source for popovers is a thoughtful detail that will help developers build more robust and accessible UI components. The element-scoped keyword for random() is a niche but powerful tool for dynamic styling. These aren't headline-grabbing features, but they represent steady progress in making the web platform more capable and developer-friendly.