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-ui-invalid CSS pseudo-class represents any validated form element whose value isn't valid based on their validation constraints, in certain circumstances. This pseudo-class is applied according to the following rules:
The <basic-shape> type can be specified using basic shape functions. When using this syntax to define shapes, the reference box is defined by each property that uses <basic-shape> values. The coordinate system for the shape has its origin on the top-left corner of the reference box with the x-axis running to the right and the y-axis running downwards. All the lengths expressed in percentages are resolved from the used dimensions of the reference box.