think about the number of columns you want to display on your Archives. And decide upon the minimum width you want them displayed. A minimum column width should be around 320px as this is the average size of a Mobile display, and around a maximum of 360px.
For more columns use the smaller size eg.
3 x Post columns + 25% sidebar would be 4 x 320px = 1280px container width.
2 x Post Columns + 30% sidebar would be 3 x 360px = 1080px container width.
For the single post – the content width may be too large if you’re using those settings. But you can reduce the width using a Layout Element to say 960px for better reading widths.
To create a full width page you can use the Page Builder Container:
I am thinking of doing homepage and categories pages with no sidebar so make it 3 post columns and 2 post columns mixing it. So, I was thinking doing it 1024px width or max 1180px. But, my doubt is doesnt look very small this resolution on a mac computer hd?