While Bootstrap uses ems or
rems for defining most sizes,
pxs are used for grid breakpoints and container widths. This is because the viewport width is in pixels and does not change with the font size.
|Extra small devices (<576px)||Small devices (≥576px)||Medium devices (≥768px)||Large devices (≥992px)||Extra Large devices (≥1200px)|
|Max container width||None (auto)||540px||720px||960px||1140px|
|# of columns||12|
|Gutter width||30px (15px on each side of a column)|
Using a single set of
.col-sm-* classes, you can create a basic grid system that starts out stacked on extra small devices before becoming horizontal on desktop (medium) devices.
Move columns to the right using
.offset-md-* classes. These classes increase the left margin of a column by * columns. For example,
.col-md-4 over four columns. With the move to flexbox in v4, you can use margin utilities like
.mr-auto to force sibling columns away from one another.
To nest your content with the default grid, add a new
.row and set of
.col-sm-* columns within an existing
.col-sm-* column. Nested rows should include a set of columns that add up to 12 or fewer (it is not required that you use all 12 available columns).