Apple releases the first developer betas of iOS 27.3, iPadOS 27.3 and macOS 27.3, adding three main updates to Safari: vertical tabs, Adaptive Dark Mode, and new Siri AI actions. Several outlets describe the changes as arriving first in betas and later expanding to public testing.

Vertical Tabs move the tab interface from a horizontal bar to a layout along the left side of the browser window, using icons by default with an option to widen the bar to show titles. Adaptive Dark Mode targets sites without a built-in dark design by prompting users to “try” a darkened version, with options for site-by-site or automatic use and a stated limit where native dark-mode sites are not affected.

Outlets also highlight expanded Siri AI capabilities for browser tasks, including actions related to tabs, windows, and organization. Coverage focuses mainly on Safari, with some outlets briefly framing 27.3 as a broader platform update, while MacRumors and others include additional operational detail (for example, how Adaptive Dark Mode adapts per site and what developers can configure).