[$5] - Active/Past challenge listings in Dashboard and Profile (Mobile view)

[birdofpreyru]

This is how my challenge listing in Dashboard looks now (you may check related commits which update the styling 4363a2e, and f475776):

However, at Dashboard page with listings of past challenges, they are rendered not that nice (not centered, the first one is shifted to left, comparing to others, also the padding inside card does not collapse, http://local.topcoder.com/my-challenges/?status=completed):

Please, update so that the second page (both Active and Past tabs) looks similar to the first screenshot. Sure, it should not affect the Desktop layout of the pages.