Use flex-basis to set wp attributes base width

Signed-off-by: Alex Coles <alex@alexbcoles.com>
Make full attribute value accessible with title=""

Signed-off-by: Alex Coles <alex@alexbcoles.com>
Merge pull request #1916 from opf/fix/14596-details-pane-long-attributes

Fixes for wp attributes layout with long values [fixup]