紅底是 container padding 後的剩下的範圍
預設四個 breakpoint
Small devices (landscape phones, 576px and up)
Medium devices (tablets, 768px and up)
Large devices (desktops, 992px and up)
Extra large devices (large desktops, 1200px and up)
| Extra small 576px | Small ≥576px | Medium ≥768px | Large ≥992px | Extra large ≥1200px | |
|---|---|---|---|---|---|
| Max container width | None (auto) | 540px | 720px | 960px | 1140px |
| # of columns | 12 | ||||
| Gutter width | 30px (15px on each side of a column) | ||||