中间有箭头的下拉菜单

Question

我正在尝试创建一个像此处那样的下拉菜单，但我未能成功地为其设置正确的样式。

我要创建的菜单与找到的菜单相似 here

示例：

这就是我目前所拥有的！

@import url('http://getbootstrap.com/dist/css/bootstrap.css');
.dropdown-menu:before {
  position: absolute;
  top: -7px;
  left: 9px;
  display: inline-block;
  border-right: 7px solid transparent;
  border-bottom: 7px solid #ccc;
  border-left: 7px solid transparent;
  border-bottom-color: rgba(0, 0, 0, 0.2);
  content: '';
}
.dropdown-menu:after {
  position: absolute;
  top: -6px;
  left: 10px;
  display: inline-block;
  border-right: 6px solid transparent;
  border-bottom: 6px solid #ffffff;
  border-left: 6px solid transparent;
  content: '';
}

<div class="dropdown">
  <a data-toggle="dropdown" href="#">Dropdown trigger</a>
  <ul class="dropdown-menu" role="menu" aria-labelledby="dLabel">
    Account Settings<hr>Billing
  </ul>
</div>

我无法将箭头居中，也适用"drop down menu animation effect"

如何使箭头居中？

Answer 1

要更改箭头的位置，只需像这样更改 left 值：

.dropdown-menu:before {
  position: absolute;
  top: -7px;
  left: 40%;
  display: inline-block;
  border-right: 7px solid transparent;
  border-bottom: 7px solid #ccc;
  border-left: 7px solid transparent;
  border-bottom-color: rgba(0, 0, 0, 0.2);
  content: '';
}

.dropdown-menu:after {
  position: absolute;
  top: -6px;
  left: 40%;
  display: inline-block;
  border-right: 6px solid transparent;
  border-bottom: 6px solid #ffffff;
  border-left: 6px solid transparent;
  content: '';
}

JSFiddle

中间有箭头的下拉菜单

dropdown menu with arrow in center

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jquery

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