610 ILCS 10/3
At any such meeting, stockholders may vote in person or by proxy, each stockholder being entitled to one vote for each share of stock held by him, except as otherwise provided in the articles of incorporation or consolidation, and votes representing two-thirds of all the voting power of the outstanding stock of the company entitled to vote on any such change shall be necessary for the approval thereof; Provided, however, that for the approval of any such change in respect to the capital stock it shall also be necessary, if there be shares of more than one class outstanding, that votes representing at least a majority (or such greater proportion as the articles of incorporation or consolidation may require) of all the outstanding shares of each class be cast in favor of such approval.
610 ILCS 10/3