当我将鼠标悬停在bootstrap下拉列表上时，每个元素都不会占用相同的背景宽度

Question

我正在尝试创建一个下拉列表。我不确定代码有什么问题。当我将鼠标悬停在每个列表元素上时，它不会将整个宽度标记为红色。 here is the preview

这是我的HTML：

<!-- Navigation -->
<nav class="navbar navbar-custom">
  <div class="container">
    <div class="navbar-header">
      <button type="button" class="navbar-toggle" data-toggle="collapse" data-target="#bs-example-navbar-collapse-1" aria-expanded="false">
        <span class="sr-only">Toggle navigation</span>
        <span class="icon-bar"></span>
        <span class="icon-bar"></span>
        <span class="icon-bar"></span>
      </button>
    </div>
    <div class="collapse navbar-collapse" id="bs-example-navbar-collapse-1">
      <ul class="nav navbar-nav">
        <li>
          <a class="navbar-menu" href="#">Deals</a>
        </li>
        <li class="dropdown">
          <a href="#" class="dropdown-toggle navbar-menu-title" data-toggle="dropdown" role="button" aria-haspopup="true" aria-expanded="true">Dropdown <span class="caret"></span></a>
          <ul class="dropdown-menu">
            <li><a href="#">Action</a></li>
            <li><a href="#">Another action</a></li>
            <li><a href="#">Something else here</a></li>
          </ul>
        </li>
      </ul>
    </div>
  </div>
</nav>

这是我的CSS：

.navbar-custom {
  background-color: #128C7E;
  border-radius: 0px;
}
.navbar-custom a {
  color: #ffffff;
}
.dropdown-menu > li > a:hover,
.dropdown-menu > li > a:focus {
  background-image: none !important;
}
.dropdown-menu > li > a:hover,
.dropdown-menu > li > a:focus {
  background-color: red;
}