Microsoft Expression product team released Microsoft Expression Web Professional Service Pack 1 (SP1). Many of the enhancements came from customer requests ensuring our technology is keeping pace with current web standards and fully supports new technologies like Internet Explorer (IE) 9.
Expression Web 4 SP1 1 provides complete support for HTML 5 in the Code Editor and significant support in Design View. IntelliSense in the code editor makes it easy to insert the new HTML5 tags into your markup. Block and inline elements are easily selectable in Design View, where they can be styled and adjusted.
Expression Web 4 SP1 provides support for hundreds of new properties from the draft CSS3 specification. In addition to IntelliSense support, CSS3 is supported in the CSS Properties pane, as well as the New Style and Modify Style dialog boxes.
More Info: Expression Studio Web 4 SP1