How do you set up the grid?

Question

css

You need to customize the grid. For example, so that .col-md-8 is not 760px, but more. Where exactly in the source code is this configured?

Answer 1

bootstrap-sass there file _bootstrap.scss you can set sizes for xs sm etc

Answer 2

It is not entirely clear what exactly you want to achieve, but all settings are made in two ways.
1) getbootstrap.com/customize
2) variables.less or _variables.scss in their respective sources.