Hi Ivo, sorry, it's me again with a problem.
I use the Portfolio particle. On Desktops I would like to have 2 columns, on mobile and tablet I would like to have 1 column. I created a mobile and a desktop version of the particle and configured the number of "Columns" to 1 (mobile, tablet) and 2 (Desktop). As you recommended, in the Layout manager I created 2 module positions, one for Desktop (I added the classes hidden-phone, hidden-tablet in the block tab) and one for tablets and mobile (hidden-desktop).
Now, at a screen width of 945 pixel the desktop module is replaced by the mobile module. But the mobile module displays 3! columns. At 753 pixel it displays 2 columns and, finally, at 464 pixel it displays the 1 column I configured. Is that a bug?