Question

Is it possible select (activate) submenu in ul/ol-styled menu with [Tab] key only, so the submenu will be visible?

I tried using :focus pseudo-class

ul
    li
        a:focus
        +
        ul
            li
                a ...

and with submenu selected:

ul
    li
        a (?)
        +
        ul
            li
                a:focus ...

But I can’t select active node with CSS

Check this: http://jsfiddle.net/iegik/DKvH2/

Answer 1

If you want the complete submenue to be visible when a submenue-item has focus, I don’t see a way without Javascript.
If it is enough for you, if just the focused element is visible, you could try something like this:

.links > li:not(:hover) li a:focus {
    left: 9999em;
    position: relative;
}

This would move the focused element back where it should be, if this didn’t already happen via :hover-pseudo-class.

http://jsfiddle.net/DKvH2/1/