1. A method comprising: providing, by a computing system, a development environment, the development environment including a web page editor; receiving a command at the development environment, the command referencing an electronic document being edited or viewed in a graphical user interface of the development environment, the electronic document comprising a first element written in a markup language and a second element written in a style sheet language; analyzing a structure of the electronic document responsive to the command; identifying a relationship between the first and second elements, wherein the relationship is known to cause a rendering problem associated with a document viewer that supports the first and second elements, the rendering problem occurring when the first and second elements are specified using correct syntax and used in combination in rendering a document by the document viewer; and presenting information about the rendering problem via the development environment.