Off the top of my head, order in CSS is only important when a property is defined multiple times for a given selector, either within the same block or in separate ones. Like these examples:

    .foo {
      font-size: 12px;
      font-size: 14px; // later property wins
    }

    .bar {
      font-size: 12px;
    }

    .bar, .baz {
      font-size: 14px; // later property wins
    }

And I don't see a way to generate either of those cases only using object literals in this library.