The ::-moz-placeholderpseudo-element represents any form element displaying placeholder text. This allows web developers and theme designers to customize the appearance of placeholder text, which is a light grey color by default. This may not work well if you've changed the background color of your form fields to be a similar color, for example, so you can use this pseudo-element to change the placeholder text color.
The :-moz-system-metric(scrollbar-end-backward)CSSpseudo-class will match an element if the computer's user interface includes a backward arrow button at the end of scrollbars.
The :-moz-system-metric(scrollbar-end-forward)CSSpseudo-class will match an element if the computer's user interface includes a forward arrow button at the end of scrollbars.
The :-moz-system-metric(scrollbar-start-backward)CSSpseudo-class will match an element if the computer's user interface includes a backward arrow button at the start of scrollbars.
The :-moz-system-metric(scrollbar-start-forward)CSSpseudo-class will match an element if the computer's user interface includes a forward arrow button at the start of scrollbars.
The :-moz-system-metric(scrollbar-thumb-proportional)CSSpseudo-class will match an element if the computer's user interface uses proportional scrollbar thumbs; that is, the draggable thumb on the scrollbar resizes to indicate the relative size of the visible area of the document.
The :-moz-system-metric(touch-enabled)CSSpseudo-class will match an element if the device on which the content is being rendered offers a supported touch-screen interface.
The :-moz-system-metric(windows-default-theme) CSS pseudo-class matches an element if the user is currently using one of the following themes in Windows: Luna, Royale, Zune, or Aero (i.e., Vista Basic, Vista Standard, or Aero Glass). This will exclude Windows Classic themes as well as third-party themes.
The :out-of-range CSS pseudo-class matches when an element has its value attribute outside the specified range limitations for this element. It allows the page to give a feedback that the value currently defined using the element is outside the range limits. A value can be outside of a range if it is either smaller or larger than maximum and minimum set values.
The :visited CSS pseudo-class lets you select only links that have been visited. This style may be overridden by any other link-related pseudo-classes, that is :link, :hover, and :active, appearing in subsequent rules. In order to style appropriately links, you need to put the :visited rule after the :link rule but before the other ones, defined in the LVHA-order: :link — :visited — :hover — :active.
The additive-symbols descriptor is similar to the symbols descriptor and allows the user to specify symbols to be used for counter representations when the value of the system descriptor is additive. The additive-symbols descriptor defines what are known as additive tuples, each of which is a pair containing a symbol and a non-negative integer weight. The additive system is used to construct sign-value numbering systems such as the Roman numerals.
The fallback descriptor can be used to specify a counter style to fall back to if the current counter style cannot create a marker representation for a particular counter value. If the specified fallback style is also unable to construct a representation, then its fallback style will be used. If a valid fallback style is not specified, it defaults to decimal. A few scenarios where fallback style will be used are:
The pad descriptor can be used with custom counter style definitions when you need the marker representations to have a minimum length. If a marker representation is smaller than the specified pad length, then the marker will be padded with the specified pad symbol. Marker representations longer than the pad length are constructed as normal. Pad descriptor takes the minimum marker length as an integer and a symbol to be used for padding as the second parameter. A common usage of the pad descriptor is when you need your list to start numbering from 01 and go through 02, 03 and so on, instead of just 1, 2, 3...
The prefix descriptor of the @counter-style rule allows authors to specify a symbol that will be prepended to the marker representation. If no value is specified, the default value will be the empty string.
When defining custom counter styles, the range descriptor lets the author specify a range of counter values over which the style is applied. If a counter value is outside the specified range, then the fallback style will be used to construct the representation of that marker. Value of the range descriptor can be either auto or a comma separated list of lower and upper bounds specified as integers.
The suffix is used with @counter-style to specify a symbol that will be appended to the marker representation. A symbol can be a string, image or a CSS identifier. If not specified, the descriptor assumes the default value "\2E\20" ("." full stop followed by a space).
The symbols descriptor is used to specify the symbols that the specified counter system will use to construct counter representations. A symbol can be a string, image, or identifier. The symbols descriptor must be specified when the value of the system descriptor is cyclic, numeric, alphabetic, symbolic, or fixed. When the additive system is used, the additive-symbols descriptor is used to specify the symbols.