sidebar_second and sidebar_first have no css

There is no css class for "sidebar_second" neither for "sidebar_first", so when trying to get some blocks from there, the content of the supposed columns is displayed one under another.

so if there is nothing matching to

 <div id="sidebar-first" class="column sidebar"><div class="section">...</div></div<
    <div id="sidebar-second" class="column sidebar"><div class="section">....</div></div>

in openpublic_eu.css, what should we write in it to get the proper display ?

Thks