LIMITED POWER OF ATTORNEY


     The undersigned hereby constitutes and appoints each of Luke Valentino,
Marge Bajzek and Debra Cherry, with full power to each of them to act alone, as
his or her true and lawful attorney-in-fact to:

     (1)  execute and file in the name and on behalf of the undersigned Forms
          3, 4 and 5 pursuant to Section 16(a) of the Securities Exchange Act of
          1934 and the rules thereunder;

     (2)  do and perform any and all acts for and on behalf of the
          undersigned which may be necessary or desirable to complete the
          execution of any such Form 3, 4 or 5 and the timely filing of such
          form with the United States Securities and Exchange Commission, the
          NASDAQ Stock Market, or otherwise; and

     (3)  take any other action of any type whatsoever in connection with
          the foregoing which such attorney-in-fact in his or her sole
          discretion determines may be of benefit to, in the best interest of,
          or legally required by, the undersigned, it being understood that the
          documents executed by such attorney-in-fact on behalf of the
          undersigned pursuant to the Power of Attorney shall be in such form
          and shall contain such terms and conditions as such attorney-in-fact
          may approve in his or her discretion.

     Until such time as the undersigned is no longer subject to the obligations
imposed by Section 16, the undersigned hereby grants to each such attorney-in-
fact full power and authority to do and perform each and every act and thing
whatsoever which such attorney-in-fact in his or her sole discretion determines
to be necessary or appropriate to be done in the exercise of any of the rights
and powers herein granted, with full power of substitution or resubstitution,
hereby ratifying and confirming all that such attorney-in-fact, or his or her
substitute or substitutes, shall lawfully do or cause to be done by virtue of
this Power of Attorney and the rights and powers herein granted.  The
undersigned acknowledges that the foregoing attorneys-in-fact, in serving in
such capacity at the request of the undersigned, are not assuming any of the
undersigned's responsibilities to comply with Section 16 of the Securities
Exchange Act of 1934 and shall have no liability with respect thereto.

     IN WITNESS WHEREOF, the undersigned has caused this Power of Attorney to be
executed as of this 9th day of October, 2018.


                                          /s/ Alan Jeffrey Carr
                                          --------------------------
                                          Alan Jeffrey Carr