bcgrnd-sz.contain Полифилл, поддерживающий в IE возможность заполнения фоновой картинкой без обрезки (т.е. contain, и только оно!)

backgroundsize.min.htc

<!-- background-size-polyfill v0.2.0 | (c) 2012-2013 Louis-Rémi Babé | MIT License -->
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behaviour.css

.ie8 .some, .ie7 .same {
-ms-behavior: url(http://x/x/x//backgroundsize.min.htc);
behavior: url(http://x/x/x//backgroundsize.min.htc);
}