Make sure to edit the assets/base/_grid.scss to match the theme styling you desire. $rem-base is important for setting the media queries.
In sass/layout/_sections.scss is where the main breakpoints are located.
- Important * - to be fixed: right now the breakpoints are set using $breakpoint variable located in _variables.scss file, but the widht in the row is in pixels which is not related to the theme base rem value.