I would like to design a content first layout. The visible order should be

sidebar | content for normal layout and

sidebar
content

for mobile/stacked layout.
HTML output should always be 1. content, 2. sidebar.

To realized this I adjusted the settings for position and weight of the regions:
content position=1, weight=0
sidebar position=0, weight=1

Normal layout works well, however the order at mobile layout is wrong because the sidebar appears under the content. So is it possible to have a content first layout (in HTML) with sidebar appearing over the content for mobile layout?