I've split the code window for a long css file into two sections, top half for viewing one area of code, bottom area for viewing another area of the code. I did this by dragging the splitter on the top right of the code editor to the middle of the editing area.
What is the keystroke command that makes the cursor jump from the lower window to the upper window and vice versa?
I believe the hotkey is the same as sql server.
The F6 key moves between window splits in the default keymap.
You can find and customize all keyboard shortcuts in Visual Studio in the Keyboard Command options. If you go there and search for commands containing "split", you'll find the Window.NextSplitPane command, which is what you want. You can also map this command to another key. Keyboard shortcuts can also be context-sensitive, which means the F6 key can do different things in different situations.
Tools > Options > Environment > Keyboard