11. A computer-implemented method comprising: receiving, by an application executed by a computing system, input identifying a stylistic change to an element in a document, the element defined by markup code; responsive to the input, automatically accessing a style sheet included in the document or in a separate style sheet file referenced by the document, wherein the style sheet comprises a plurality of style sheet rules and wherein each rule is applicable to one or more elements in the document to control an appearance of the one or more elements; automatically searching the style sheet for a style sheet rule defining a style having attributes that match said stylistic change; if a style sheet rule in said style sheet matching said stylistic change is found, automatically applying the discovered style sheet rule to said content by modifying markup defining a structural element of said web page corresponding to said content; otherwise, automatically generating one or more style sheet rules for the stylistic change and updating the style sheet to include the generated one or more style sheet rules; and automatically applying the generated style sheet rule to said element by changing the markup code defining the element to reference the style sheet rule.
11. A computer-implemented method comprising: receiving, by an application executed by a computing system, input identifying a stylistic change to an element in a document, the element defined by markup code; responsive to the input, automatically accessing a style sheet included in the document or in a separate style sheet file referenced by the document, wherein the style sheet comprises a plurality of style sheet rules and wherein each rule is applicable to one or more elements in the document to control an appearance of the one or more elements; automatically searching the style sheet for a style sheet rule defining a style having attributes that match said stylistic change; if a style sheet rule in said style sheet matching said stylistic change is found, automatically applying the discovered style sheet rule to said content by modifying markup defining a structural element of said web page corresponding to said content; otherwise, automatically generating one or more style sheet rules for the stylistic change and updating the style sheet to include the generated one or more style sheet rules; and automatically applying the generated style sheet rule to said element by changing the markup code defining the element to reference the style sheet rule. 13. The computer-readable medium of claim 11 , wherein the style sheet comprises a cascading style sheet.