em
s or rem
s for defining most sizes, px
s 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. See how aspects of the Bootstrap grid system work across multiple devices with a handy table.
Extra small <576px |
Small ≥576px |
Medium ≥768px |
Large ≥992px |
Extra large ≥1200px |
|
---|---|---|---|---|---|
Max container width | None (auto) | 540px | 720px | 960px | 1140px |
Class prefix |
.col-
|
.col-sm-
|
.col-md-
|
.col-lg-
|
.col-xl-
|
# of columns | 12 | ||||
Gutter width | 30px (15px on each side of a column) | ||||
Nestable | Yes | ||||
Column ordering | Yes |
.col-md-*
grid classes, you can create a basic grid system that starts out stacked on mobile devices and tablet devices (the extra small to small range) before becoming horizontal on desktop (medium) devices. Place grid columns within any .row
.
col-{breakpoint}-auto
classes to size columns based on the natural width of their content.
.order-
classes for controlling the visual orderof your content. These classes are responsive, so you can set the order
by breakpoint (e.g., .order-1.order-md-2
). Includes support for 1
through 12
across all five grid tiers.
.order-first
and .order-last
classes that change the order
of an element by applying order: -1
and order: 13
(order: $columns + 1
), respectively. These classes can also be intermixed with the numbered .order-*
classes as needed.
.offset-md-*
classes. These classes increase the left margin of a column by *
columns. For example, .offset-md-4
moves .col-md-4
over four columns.
.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).