Bootstrap 4 responsive navbar vertical

问题

I am using Bootstrap 4 and have navigation with horizontal items on my page. On small devices this menu collapses and menu items are still in horizontal line. What should I do to change it to vertical so items are one per each line?

回答1:

For Bootstrap 4, the breakpoints have changed. You should override the navbar CSS like this if you want it to be vertical on small screens:

@media(max-width: 544px) {
    .navbar .navbar-nav>.nav-item {
        float: none;
        margin-left: .1rem;
    }
    .navbar .navbar-nav {
        float:none !important;
    }
    .navbar .collapse.in, .navbar .collapsing  {
        clear:both;
    }
}

Demo http://codeply.com/go/Ar1H2G4JVH

Note: The @media query max-width should be adjusted accordingly for the navbar-toggleable-* class used in the navbar.

• navbar-toggleable-xs - 544px
• navbar-toggleable-sm - 767px
• navbar-toggleable-md - 991px

UPDATE: The extra CSS is no longer needed as of Bootstrap 4 Alpha 6 since the navbar will stack vertically: http://www.codeply.com/go/cCZz5CsMcD

来源：https://stackoverflow.com/questions/36329305/bootstrap-4-responsive-navbar-vertical