June 2026 Baseline: form controls get content-aware sizing
The June 2026 Baseline update brings one new feature into the "Newly available" tier and promotes a broad set of CSS, HTML, and Web API features to "Widely available." The headline addition is field-sizing, which lets form controls size themselves based on their content, potentially eliminating the need for JavaScript auto-resize workarounds.
Also new this month: Baseline Alerts on the Web Platform Status dashboard. After signing in with GitHub, developers can subscribe to notifications when features reach Newly or Widely available status or gain new browser implementations. Alerts support email, RSS, and Slack webhooks, with scheduling from immediate to monthly. Subscriptions can target saved searches such as all HTML features, and can generate shareable feature lists or custom newsletters.
Newly available: field-sizing
The CSS field-sizing property controls how form elements like <textarea>, <input>, and <select> determine their dimensions. These controls traditionally have fixed default sizes, but field-sizing: content makes them expand or shrink to match their content, removing the need for custom resize scripts.
Widely available this month
The following features are now considered broadly compatible and ready for production use across the core browser set.
CSS features
The :has() pseudo-class allows styling an element based on its descendants or subsequent siblings, enabling conditional layouts without JavaScript DOM inspection. The CSS nesting selector & anchors child rules to their parents, clarifying specificity in nested hover, focus, or pseudo-class states.
The cap length unit is now widely available, providing a font-relative measurement based on uppercase letter height for precise typographic alignment. The pow() function brings exponential math directly into CSS declarations, useful for responsive scaling. The counter-set property complements counter-reset and counter-increment for controlling list numbering and custom counters.
Other CSS additions include the <easing-function> data type with support for linear() and custom spring or bounce curves, the mask shorthand for image-based clipping, the :dir() pseudo-class for matching text directionality, and the @media (scripting) feature for testing JavaScript availability in progressive enhancement scenarios.
HTML and Web API features
HTMLIFrameElement.loading brings lazy loading to embedded frames by deferring offscreen iframes until near the viewport. The responsive preloading pattern now works broadly with media queries on <link rel="preload">, letting browsers fetch only assets matching the user's environment.
On the canvas side, CanvasRenderingContext2D.reset() clears a context's transformations, clipping, and styles back to defaults for clean reuse. The createImageBitmap() static method decodes images from sources like <img>, <canvas>, Blob, or ImageData off the main thread, avoiding UI blocking in canvas-heavy work.
The preservesPitch property on <audio> and <video> elements controls whether pitch changes when playbackRate is modified. The URL.canParse() static method validates URL strings without throwing exceptions. Finally, the Storage Access API is now widely available, letting cross-site iframes request unpartitioned cookie and storage access for authentication and stateful interactions across domains.
If something Baseline-related was missed in this round, the project's issue tracker is open for submissions to future editions.
