Bootstrap includes a responsive, mobile first fluid grid system that appropriately scales up to 12 columns as the device or viewport size increases. It includes predefined classes for easy layout options, as well as powerful mixins for generating more semantic layouts.
See how aspects of the Bootstrap grid system work across multiple devices with a handy table.
|Extra small devices Phones (<768px)||Small devices Tablets (≥768px)||Medium devices Desktops (≥992px)||Large devices Desktops (≥1200px)|
|Grid behavior||Horizontal at all times||Collapsed to start, horizontal above breakpoints|
|Container width||None (auto)||750px||970px||1170px|
|# of columns||12|
|Gutter width||30px (15px on each side of a column)|
Using a single set of .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 in any .row.
Example: Mobile and desktop
Don't want your columns to simply stack in smaller devices? Use the extra small and medium device grid classes by adding .col-xs-* .col-md-* to your columns. See the example below for a better idea of how it all works..
Example: Mobile, tablet, desktop
Build on the previous example by creating even more dynamic and powerful layouts with tablet .col-sm-* classes.
Example: Column wrapping
If more than 12 columns are placed within a single row, each group of extra columns will, as one unit, wrap onto a new line.
Since 9 + 4 = 13 > 12, this 4-column-wide div gets wrapped onto a new line as one contiguous unit.
Subsequent columns continue along the new line.
Responsive column resets
With the four tiers of grids available you're bound to run into issues where, at certain breakpoints, your columns don't clear quite right as one is taller than the other. To fix that, use a combination of a .clearfix and our responsive utility classes.
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).
Easily change the order of our built-in grid columns with .col-md-push-* and .col-md-pull-* modifier classes.