unequal columns in squarespace

I am using this custom code to create three columns on my page.

https://www.legendsmarketing.com/marketing-revised

@media screen and (min-width: 640px) { #block-289a8ff4664d4ac14fe2>div {
    column-count: 3;
    column-gap: 25px;
  }
}

But I am wanted to create make the columns different width. The first one I would like to take up about 60% of the width and the other 2 to take up about 20% each. Is there away to do this?

I don't believe you can do that with columns, but you would be able to if you could use grid instead.