Remove multi column using json

Hi,

I added JSON formatting code to my Sharepoint list form in order to add sections. After doing this, the form got multiple columns (the fields are stacked in multiple columns depending on window width). Before adding JSON, the form had one column only.

Is there a way to keep one column ONLY when adding sections?

JSON code I'm using:

{
    "sections": [
        {
            "displayname": "Section 1",
            "fields": [
                "Title"
            ]
        },
        {
            "displayname": "Section 2",
            "fields": [
          	    ........
            ]
        }
    ]
}

Best,

Markus