When så describes a consequence it usually translates into so and the phrase is a straight forward main clause. But if the consequence at the same time is a change of the situation the meaning will be And then and the phrase will be inverted. So:
Det var mørkt, så jeg (s) kunne (v) ikke (a) se.(It was dark, so I could not see.)

And then:
Lyset gik ud. Så kunne (v) jeg (s) ikke (a) se noget. (The light went out and then I could not see.)
Drag and drop to form a så-sentence. The sequence sva means so and vsa means and then.