COLR/CPAL(v0) Font Formats
The COLR table adds support for multi-colored glyphs in a manner that integrates with the rasterizers of existing text engines. COLRv0 only supports pure colors, does not support gradients, transformations and various blending modes.
If a font has multiple types of variations based on the width of characters, the `font-stretch` property allows the appropriate one to be selected. The property in itself does not cause the browser to stretch to a font.
CSS Generated content for pseudo-elements
Method of displaying text or images before or after the given element's contents using the ::before and ::after pseudo-elements. All browsers with support also support the `attr()` notation in the `content` property.
Do Not Track API
API to allow the browser's Do Not Track setting to be queried via `navigator.doNotTrack`. Due to lack of adoption the Do Not Track specification was deprecated in 2018.
DOM manipulation convenience methods
jQuery-like methods on DOM nodes to insert nodes around or within a node, or to replace one node with another. These methods accept any number of DOM nodes or HTML strings as arguments. Includes: `ChildNode.before`, `ChildNode.after`, `ChildNode.replaceWith`, `ParentNode.prepend`, and `ParentNode.append`.
readonly attribute of input and textarea elements
Makes the form control non-editable. Unlike the `disabled` attribute, `readonly` form controls are still included in form submissions and the user can still select (but not edit) their value text.
navigator api: donottrack
window api: `beforeunload` event: dialog displays a generic string, not event handler return value