A User interface stylesheet language is a stylesheet language which is meant to be applied to graphical computer user interfaces. They primarily act as subsidiary languages to style UI elements which are either programmed or marked-up (as in XML-based markup languages).
Examples Cascading Style Sheets as used in Mozilla's XUL user interface Qt Style Sheets as used in KDE4 Robert Staudinger's CSS theming for GTK+Ars Technica article
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