Two columns to 1 column

Hi,

First of all, this is an amazing plugin. Thanks!

I made a list on this page https://www.mibomachines.com/mibo/

As you can see the list has two columns now, but I would like to have only one column. So, the second post needs to be underneath the first one.

This is my CSS at the moment:

#w4pl-list-[listid] .postItem{
  float: left;
  margin:0 1% 30px;
}
@media screen and ( min-width: 480px ) {
  #w4pl-list-[listid] .postItem{width:48%;}
}
@media screen and ( max-width: 480px ) {
  #w4pl-list-[listid] .postItem{width:98%;}
}
#w4pl-list-[listid] .postItem img {
  float: left;
  margin: 0 30px 30px;
}