For instance, if an element in the document tree has a value of 'none' for the 'display' property, that element will generate nothing in the rendering structure. Steps 2-5 are addressed by the bulk of this specification. Step 6 lies outside the scope of this specification. The canvas is infinite for each dimension of the space, but rendering generally occurs within a finite region of the canvas, established by the user agent according to the target medium. For instance, user agents rendering to a screen generally impose a minimum width and choose an initial width based on the dimensions of the viewport .
User agents rendering to a page generally impose width and height constraints.
Aural user agents may impose limits in audio space, but not in time. Some aspects of the canvas where the document will be rendered. User agents supporting CSS2 will be able to understand CSS1 style sheets, while CSS1 user agents are able to read CSS2 style sheets and discarding parts they don't understand. Also, user agents with no CSS support will be able to view style-enhances documents. Of course, the stylistic enhancements made possible by CSS will not be rendered, but all content will be presented.