The :-moz-first-nodeCSSpseudo-class represents any element that is the first child node of some other element. It differs from :first-child because it does not match a first child element with (non-whitespace) text before it.
The :-moz-focusringCSSpseudo-class is similar to the :focus pseudo-class, but it only matches an element if the element is currently focused and a focus ring or other indicator should be drawn for that element. If :-moz-focusring matches, then :focus also matches, but the converse is not always true - it depends on whether the user agent has focus ring drawing enabled and how the element was focused. Whether the user agent has focus ring drawing enabled can depend on things like the settings of the operating system the user is using, so the precise behavior of this pseudo-class can vary from platform to platform depending on each platforms' particular focus best practices (defaults) or user modified settings.
The :-moz-last-nodeCSSpseudo-class matches an element that is the last child node of some other element. It differs from :last-child because it does not match a last child element with (non-whitespace) text after it.
The@counter-styleCSSat-rule lets authors define specific counter styles that are not part of the predefined set of styles. A @counter-style rule defines how to convert a counter value into a string representation.
In combination with elevation, azimuth enables different audio sources to be positioned spatially for aural presentation. This is important in that it provides a natural way to tell several voices apart, as each can be positioned to originate at a different location on the sound stage. Stereo output produce a lateral sound stage, while binaural headphones and multi-speaker setups allow for a fully three-dimensional stage.
The > combinator separates two selectors and matches only those elements matched by the second selector that are direct children of elements matched by the first. By contrast, when two selectors are combined with the descendant selector, the combined selector expression matches those elements matched by the second selector for which there exists an ancestor element matched by the first selector, regardless of the number of "hops" up the DOM.
CSS Flexible Box Layout is a module of CSS that defines a CSS box model optimized for user interface design. In the flex layout model, the children of a flex container can be laid out in any direction, and can “flex” their sizes, either growing to fill unused space or shrinking to avoid overflowing the parent. Both horizontal and vertical alignment of the children can be easily manipulated. Nesting of these boxes (horizontal inside vertical, or vertical inside horizontal) can be used to build layouts in two dimensions.
CSS Images is a module of CSS that defines what types of images can be used (the <image> type, containing URLs, gradients and other types of images), how to resize them and how they, and other replaced content, interact with the different layout models.