Part of my job is to be able to change the css of a Sharepoint 2010 enterprise site. I've the possibility to use Sharepoint Designer. I've used it to make a copy of v4.master, set it as master page, added a few lines:
<SharePoint:CssRegistration runat="server" name="/Style Library/... myfile.css" After="corev4.css"/>
<SharePoint:CssRegistration runat="server" name="/Style Library/... myfile.css" After="corev4.css"/>
Two questions:
1) Is there any danger in making a new master page via Sharepopint Designer if you only add these lines of code?
I've seen some people writing about Sharepoint Designer being a little risky. I'm no coder myself. My only use of SP Designer is adding these lines in a master page and editing the CSS in Style Library.
2) We have lots of subsites. When I want to change the design on just one or two of these, should I continue the same path and add a uniqe css file in Style Library and link this file in a master page copy on the subsite?