CSS selector for a child element whose parent element has a certain class

To select strong elements that are descendants of an element with class commandBar, use the descendant combinator along with a class selector:

.commandBar strong

In order to only select direct children strong elements, use the child combinator, >:

.commandBar > strong

Depending on your markup, you may also want to specify the element type that has the class .commandBar (in this case, div):

div.commandBar strong