Usiung "Implement interface members" on ASP.NET webpage which uses master page adds incorrect <HEAD><BODY> tags. the root element for such pages is <asp:Content>
1. Open web page with master page
2. Add <%@ Implements Interface=ISomething">
3. Use R# Generate and choose Interface members on ISomething
R# generates implementation, but wraps it into <BODY><HEAD> - not allowed here