XPath: all elements with only non-parent children with

I'm looking for an XPath which returns all elements that
  * have only children that are no parents
    (= have no children @ all: no textnodes, no whitespace nodes, etc)
    * all of those (diverse) children have a style attribute with
      the exact same value

<root>
  <foo>
   <bar style="baz"/>
   <blah style="baz"/>
   <blam style="baz"/>
  </foo>
</root>

TIA,
Tobi

--
Tobias Reif
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