The roundRect() methods draw a rounded rectangle to a 2D canvas.

The inert HTML attribute marks an element and its descendants as non-interactive. Inert elements don't get focus or fire click events.

The CSSStyleSheet constructor creates a new stylesheet which can be shared between a document and multiple shadow roots using adoptedStyleSheets.

128-bit SIMD (Single Instruction Multiple Data) performs one instruction on multiple units of data, when running on hardware that supports such instructions. Also known as vector instructions.

Custom elements may act like built-in form elements, via the attachInternals() method of HTMLElement and the ElementInternals API.

The assign() method for <slot> elements assigns nodes to the slot, as an alternative to using the slot and name HTML attributes. The nodes must be children of a shadow host and the shadow root must be created with the slotAssignment set to "manual". Also known as manual slot assignment.

A <script type="importmap"> HTML element provides an import map as a JSON string. An import map controls how the browser should resolve module specifiers when importing JavaScript modules.

The range syntax of CSS media queries allows you to use mathematical comparison operators such as <, >, <=, and >= to define a range of values for a media query. For example, (400px < width < 1000px) returns true if the viewport width is between 400px and 1000px.

Notifications via service worker registration's showNotification() method, sent from installed web applications (for example, saved to the Home Screen on Safari for iOS), show a message to the user, typically using the notification system of the host operating system.

The OffscreenCanvas API provides a canvas that can be drawn to off screen, with no dependencies on the DOM, which can be used to run heavy rendering operations inside a worker context.

The navigator.storage.getDirectory() method returns a FileSystemDirectoryHandle that is restricted to a specific origin and invisible to the user's actual file system for faster file-based applications, such as SQLite databases.

The Push API subscribes to and receives server-initiated messages. Subscribers receive pushed messages in the background, even after periods inactive or offline.

The decodedBodySize, encodedBodySize, and transferSize properties of the PerformanceResourceTiming API reports the size of resources loaded.

The screen.orientation API gets information about the orientation of the viewport, such as landscape or portrait. With this API, you can adapt an application's layout or behavior in response to changes in orientation.

The serverTiming property of the PerformanceResourceTiming API contains server timing information about network requests.

The font-synthesis-small-caps CSS property sets whether or not the browser should synthesize small caps typefaces when they're missing from the font.

The font-synthesis-style CSS property sets whether or not the browser should synthesize italic and oblique typefaces when they're missing from the font.

The font-synthesis-weight CSS property sets whether or not the browser should synthesize bold typefaces when they're missing from the font.

The messageerror event fires on a target, such as a window or worker, when an incoming message cannot be deserialized. This event can fire for many types of messages, such as cross-document messages or broadcast channel messages.

The outline CSS shorthand sets the color, style, and width of a line around an element, outside of the border.

The navigator.pdfViewerEnabled property is a boolean for whether the browser navigates to and shows a PDF in the browser window or downloads the PDF.

The requestAnimationFrame() method in workers schedules a function that runs before the next repaint. Together with offscreen canvas, you can animate content from a worker.

The translate HTML attribute marks whether an element's text should be translated.

The sin(), cos(), tan(), asin(), acos(), atan(), and atan2() CSS functions compute various trigonometric functions.

The font-variant-alternates CSS property, along with the @font-feature-values at-rule, chooses when to use a font's alternate glyphs.

Container size queries with the @container at-rule apply styles to an element based on the dimensions of its container.

The color-gamut media query sets styles based on the colors a device can display.

MathML, or the Mathematical Markup Language, describes mathematical notation, such as expressions and formulas. Also known as MathML Core.

The OES_draw_buffers_indexed extension for WebGL 2.0 contexts allows you to control blending on a per-color basis when writing to multiple color buffers simultaneously.

The sv*, lv*, and dv* CSS viewport units are relative to the smallest, largest, and current (dynamic) viewport size. They are used to size elements in relation to the viewport's dimensions.