ok now I get it, thank you! I thought I could force the columns over in a 12 column grid by having 1,2,2,2,2,2,1 to make up the 12 columns (with the single columns being blank), but I didn’t realise that the column widths had to divide evenly into 12.
I will use the page builder instead as I am totally not ready for custom responsive HTML, being my first website and all 😉