你的小提琴对我来说并不完全清楚。您的导航栏没有 .navbar 类,您的导航菜单没有 .navbar-nav。
您可以尝试添加如下所示的 CSS 代码:
.dropdown-menu,
.open > .dropdown-menu,
.dropdown-menu,
.open > .dropdown-menu .dropdown-menu {
display: block;
max-height: 0;
overflow-y:hidden;
visibility: hidden;
-webkit-transition: max-height 2s ease-in-out, visibility 1.8s ease-in;
-moz-transition: max-height 2s ease-in-out, visibility 1.8s ease-in;
-o-transition: max-height 2s ease-in-out, visibility 1.8s ease-in;
transition: max-height 2s ease-in-out, visibility 1.8s ease-in;
max-width: 100%;
}
.navbar-nav > li.open > .dropdown-menu,
.nav-pills > li.open > .dropdown-menu,
.nav-pills > li.open > .dropdown-menu .open .dropdown-menu {
max-height: 500px;
display: block;
visibility: visible;
-webkit-transition: max-height 2s ease-in-out, visibility 0s linear 0.5s;
-moz-transition: max-height 2s ease-in-out, visibility 0s linear 0.5s;
-o-transition: max-height 2s ease-in-out, visibility 0s linear 0.5s;
transition: max-height 2s ease-in-out, visibility 0s linear 0.5s;
-webkit-transition-delay: 0s;
-moz-transition-delay: 0s;
-o-transition-delay: 0s;
transition-delay: 0s;
}
演示:http://jsfiddle.net/hhb9u7db/1/
资源:
- Transitions on the display: property
- http://davidwalsh.name/css-slide
对于 Bootstrap 默认导航栏,您可以使用以下 Less 代码:
.dropdown-menu, .open > .dropdown-menu,
{
display:block;
max-height: 0;
overflow-y:hidden;
visibility:hidden;
transition:max-height 2s ease-in-out, visibility 1.8s ease-in;
max-width: 100%;
}
.navbar-nav > li.open > .dropdown-menu,
{
max-height: 500px;
display:block;
visibility:visible;
transition:max-height 2s ease-in-out, visibility 0s linear 0.5s;
transition-delay:0s;
}
使用autoprefix plugin 编译成以下 CSS 代码 (lessc --autoprefix="Android 2.3,Android >= 4,Chrome >= 20,Firefox >= 24,Explorer >= 8,iOS >= 6,Opera >= 12,Safari >= 6"):
.dropdown-menu,
.open > .dropdown-menu {
display: block;
max-height: 0;
overflow-y:hidden;
visibility: hidden;
-webkit-transition: max-height 2s ease-in-out, visibility 1.8s ease-in;
-o-transition: max-height 2s ease-in-out, visibility 1.8s ease-in;
transition: max-height 2s ease-in-out, visibility 1.8s ease-in;
max-width: 100%;
}
.navbar-nav > li.open > .dropdown-menu {
max-height: 500px;
display: block;
visibility: visible;
-webkit-transition: max-height 2s ease-in-out, visibility 0s linear 0.5s;
-o-transition: max-height 2s ease-in-out, visibility 0s linear 0.5s;
transition: max-height 2s ease-in-out, visibility 0s linear 0.5s;
-webkit-transition-delay: 0s;
-o-transition-delay: 0s;
transition-delay: 0s;
}
演示:http://www.bootply.com/dd5aFlGTTE