为了更快地进行移动设备开发，请使用响应式显示类来按设备显示和隐藏元素。避免创建相同站点的完全不同版本，而是相应地为每个屏幕大小隐藏元素。
要隐藏元素，只需使用.d-none类或其中一个.d-{sm,md,lg,xl}-none类进行任何响应式屏幕变化。
要仅在给定的屏幕尺寸间隔上显示元素，您可以将一个.d--none类与一个.d--*类组合在一起，例如，.d-none .d-md-block .d-xl-none将隐藏所有屏幕尺寸的元素，中型和大型设备除外。
Show/hide for breakpoint and down:
hidden-xs-down (hidden-xs) = d-none d-sm-block
hidden-sm-down (hidden-sm hidden-xs) = d-none d-md-block
hidden-md-down (hidden-md hidden-sm hidden-xs) = d-none d-lg-block
hidden-lg-down = d-none d-xl-block
hidden-xl-down (n/a 3.x) = d-none (same as hidden)
Show/hide for breakpoint and up:
hidden-xs-up = d-none (same as hidden)
hidden-sm-up = d-sm-none
hidden-md-up = d-md-none
hidden-lg-up = d-lg-none
hidden-xl-up (n/a 3.x) = d-xl-none
Show/hide only for a single breakpoint:
hidden-xs (only) = d-none d-sm-block (same as hidden-xs-down)
hidden-sm (only) = d-block d-sm-none d-md-block
hidden-md (only) = d-block d-md-none d-lg-block
hidden-lg (only) = d-block d-lg-none d-xl-block
hidden-xl (n/a 3.x) = d-block d-xl-none
visible-xs (only) = d-block d-sm-none
visible-sm (only) = d-none d-sm-block d-md-none
visible-md (only) = d-none d-md-block d-lg-none
visible-lg (only) = d-none d-lg-block d-xl-none
visible-xl (n/a 3.x) = d-none d-xl-block
直观表示图
微信公众号 
