Semantic compression of cascading style sheets

One or more computer-readable storage media storing information to enable a computing device to perform a process, the process comprising:

• receiving a markup page comprising markup elements and a reference to a cascading style sheet;
• based on the reference to the cascading style sheet, retrieving the cascading style sheet, the cascading style sheet comprising a plurality of style rules, each style rule comprising a selector and one or more declarations, each declaration identifying a property and a value;
• applying the cascading style sheet to the markup page to identify one or more of the style rules as either redundant with respect to the markup page or inapplicable to the markup page;
• and
• generating a compressed cascading style sheet comprised of some of the style rules from the cascading style sheet, wherein a style rule identified as either redundant or inapplicable is not included in the compressed cascading style sheet.

A method performed by one or more computing devices, the method comprising:

• using a markup page to select one or more target style rules in a cascading style sheet that is associated with the markup page for the purpose of a browser rendering the markup page;
• deleting the selected one or more target style rules from the cascading style sheet;
• and
• after the deleting, storing the cascading style sheet as a compressed cascading style sheet.