Bootstrap includes a powerful mobile-first flexbox grid system for building layouts of all shapes and sizes. It’s based on a 12 column layout and has multiple tiers, one for each media query range. You can use it with Sass mixins or our predefined classes.
Setting one column width
Variable width content
Stacked to horizontal
Mix and match
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.