How to dynamically change the CSS style of a node-type?
Unless you have a ton of CSS you should add the CSS for all the nodes and use the node type class on the wrapper div of the node.

I can't remember the exact classes you can view them in the source. You could do something like this

.node {}
.node-page {}
.node-blog {}


Where the first class is on all nodes and the latter is dynamic for the node.