HTML代码

<div class="btn-group">
  <span class="btn btn-primary radius">左边按钮</span>
  <span class="btn btn-default radius">中间按钮</span>
  <span class="btn btn-default radius">中间按钮</span>
  <span class="btn btn-default radius">右边按钮</span>
</div>

CSS代码

.btn-group{ font-size:0}
.btn-group .btn{ margin-left:-1px}
.btn-group .btn:not(:first-child):not(:last-child):not(.dropdown-toggle){ border-radius:0}
.btn-group > .btn:first-child:not(:last-child):not(.dropdown-toggle){border-bottom-right-radius: 0;border-top-right-radius: 0}
.btn-group > .btn:last-child:not(:first-child),.btn-group > .dropdown-toggle:not(:first-child) {border-bottom-left-radius: 0;border-top-left-radius: 0}