Bootstrap响应式导航由768px变成992px的实现代码

<!--响应式导航部分--> 
<header role="banner"> 
  <nav role="navigation" class="navbar navbar-static-top navbar-default"> 
    <div class="container "> 
      <div class="navbar-header"> 
        <!--设置手风琴式的navbar，然后类navbar-toggle包装在屏幕大于992px，隐藏--> 
        <button type="button" class="navbar-toggle" data-toggle="collapse" data-target="#navbar-collapse"> 
          <!--这里的span.icon-bar 是用来在按钮中画三条线--> 
          <span class="icon-bar"></span> 
          <span class="icon-bar"></span> 
          <span class="icon-bar"></span> 
        </button> 
        <a class="navbar-brand" href="index.html" rel="external nofollow" rel="external nofollow" ><img src="img/logo.png" alt="Bootstrappin'" width="120"></a> 
        <!--这里的商标图一定要设置宽度--> 
      </div> 
      <!--这里的类collapse保证默认包裹的菜单是隐藏的，如果 替换为 in 则显示--> 
      <div class="navbar-collapse collapse" id="navbar-collapse"> 
        <ul class="nav navbar-nav"> 
          <li class="active"><a href="index.html" rel="external nofollow" rel="external nofollow" > 
            <span class="icon fa fa-home "></span> Home</a></li> 
          <li><a href="#" rel="external nofollow" rel="external nofollow" rel="external nofollow" > 
            <span class="icon fa fa-desktop"></span> Portfolio</a></li> 
          <li><a href="#" rel="external nofollow" rel="external nofollow" rel="external nofollow" > 
            <span class="icon fa fa-group "></span> Team</a></li> 
          <li><a href="#" rel="external nofollow" rel="external nofollow" rel="external nofollow" > 
            <span class="icon fa fa-envelope "></span> Contact</a></li> 
        </ul> 
      </div><!--/.nav-collapse --> 
    </div><!--/.container --> 
  </nav> 
</header> 

//bootstrap.css 
@media (min-width: 992px) { 
 .navbar-toggle { 
  display: none; 
 } 
} 

//navbar.less  
.navbar-toggle { 
 position: relative; 
 float: right; 
 margin-right: @navbar-padding-horizontal; 
 padding: 9px 10px; 
 .navbar-vertical-align(34px); 
 background-color: transparent; 
 border: 1px solid transparent; 
 border-radius: @border-radius-base; 
 // Bars 
 .icon-bar { 
  display: block; 
  width: 22px; 
  height: 2px; 
  border-radius: 1px; 
 } 
 .icon-bar + .icon-bar { 
  margin-top: 4px; 
 } 
 @media (min-width: @grid-float-breakpoint) { //@grid-float-breakpoint 
  display: none; 
 } 
} 
//variables.less 
@grid-float-breakpoint:   @screen-sm-min;  //想要改成992px这里就要用这个 @grid-float-breakpoint:   @screen-md-min; 
//-------- 
@screen-sm:         768px; 
@screen-sm-min:       @screen-sm; 
@screen-md:         992px; 
@screen-md-min:       @screen-md; 
@screen-desktop:       @screen-md-min; 
// Large screen / wide desktop 
// Note: Deprecated @screen-lg and @screen-lg-desktop as of v3.0.1 
@screen-lg:         1200px; 
@screen-lg-min:       @screen-lg; 
@screen-lg-desktop:     @screen-lg-min; 

//__bootstrap.less 
//@import "navbar.less";  
@import "_navbar.less"; 
//@import "variables.less"; 
@import "_variables.less";