formula for calculating margin?

[ghost]

on the previous responsive site I did, I set a max-width for each media query, then I used a spreadsheet to calculate percentage values for the widths and margins.
For example max-width : 748px
then if I want a width of 2 columns, I'd do( 2 x column width + 1x gutter width) / max-width
how did you get to the values that yo uuse for example in this declaration:
header, #twoway {
margin: 0 27.77777777777778%;
}

thanks
Paul

[paulburgess]

Yes, this part is confusing me a tad... any help on how you calculate that margin would be great!

I understand the target / context formula but can't see how it applies here.

[torkiljohnsen]

The calculations can be seen in the LESS and SASS stylesheet variants. I /think/ Joni uses LESS in his work, and that CSS files in this project are compiled LESS files. LESS and SASS are great tools, because they allow you to use all kinds of simplifying helpers in CSS, like functions, variables, mixins and more :)

Regarding how he ends up with the value 27.7777777778%:

If you check out GGS.less, you'll see that 1 column width is calculated as 100%/18 (≈ 5.55555556%)

Then, in the 87em media query, this is added:

header, #twoway {
    margin: 0 @column*5;
}

5.55555556% * 5 ≈ 27.7777778%

[paulburgess]

Ah yes indeed, once I got into the SASS file it made more sense. Your comment helps too - thanks very much.