具有transform属性的元素内部的子元素z-index问题

Question

我有一个问题，想知道你们能否帮助我解决。

如代码片段所示，我有一些元素。

transform: translate(0,0);

然后，在它们里面，我有一个“下拉菜单”元素，当你点击按钮时它会显示出来。

问题出现在这个下拉菜单的一部分被其他元素遮挡了，我发现这是因为它的父元素有transform属性。

我的代码有更多的东西，这只是一个示例。我无法摆脱变换属性。

我想知道是否有任何解决方案。我正在尝试仅使用CSS来解决它。

干杯！！

$(document).ready(function() {
  $('button[name="button"]').click(function(e) {
    $(e.currentTarget).parent().find('.template-options-dropdown').toggleClass('open');
  });
});

.boxes {
  list-style-type: none;
}

.boxes >li {
  float: left;
  width: 100px;
  height: 100px;
  background-color: red;
  margin: 5px;
  transform: translate(0, 0);
}

.download-container {
  background: rgba(40, 39, 39, 0.8);
  bottom: 0;
  position: absolute;
  text-align: center;
  width: 100%;
}

.download-container .dropdown-container {
  display: inline-block;
  position: relative;
}

.download-container .dropdown-container button {
  background: #0bb9ab;
  color: #fff;
  padding: 6px 12px;
}

.template-options-dropdown {
  list-style-type: none;
  text-align: left;
  padding: 0;
  position: absolute;
  background-color: #111;
  visibility: hidden;
}

.template-options-dropdown.open {
  visibility: visible;
}

.template-options-dropdown li a {
  color: white;
  text-decoration: none;
}

<script src="https://ajax.googleapis.com/ajax/libs/jquery/2.1.1/jquery.min.js"></script>
<ul class="boxes">
  <li>
    <div class="download-container">
      <div class="dropdown-container">
        <button type="button" name="button">Download</button>

        <ul class="template-options-dropdown">
          <li>
            <a href="#">Original</a>
          </li>
          <li>
            <a href="#">Thumb</a>
          </li>
          <li>
            <a href="#">Mobile</a>
          </li>
          <li>
            <a href="#">Tab</a>
          </li>
          <li>
            <a href="#">Web</a>
          </li>
          <li>
            <a href="#">Large web</a>
          </li>
        </ul>
      </div>
    </div>
  </li>
  <li><div class="download-container">
      <div class="dropdown-container">
        <button type="button" name="button">Download</button>

        <ul class="template-options-dropdown">
          <li>
            <a href="#">Original</a>
          </li>
          <li>
            <a href="#">Thumb</a>
          </li>
          <li>
            <a href="#">Mobile</a>
          </li>
          <li>
            <a href="#">Tab</a>
          </li>
          <li>
            <a href="#">Web</a>
          </li>
          <li>
            <a href="#">Large web</a>
          </li>
        </ul>
      </div>
    </div></li>
  <li><div class="download-container">
      <div class="dropdown-container">
        <button type="button" name="button">Download</button>

        <ul class="template-options-dropdown">
          <li>
            <a href="#">Original</a>
          </li>
          <li>
            <a href="#">Thumb</a>
          </li>
          <li>
            <a href="#">Mobile</a>
          </li>
          <li>
            <a href="#">Tab</a>
          </li>
          <li>
            <a href="#">Web</a>
          </li>
          <li>
            <a href="#">Large web</a>
          </li>
        </ul>
      </div>
    </div></li>
  <li><div class="download-container">
      <div class="dropdown-container">
        <button type="button" name="button">Download</button>

        <ul class="template-options-dropdown">
          <li>
            <a href="#">Original</a>
          </li>
          <li>
            <a href="#">Thumb</a>
          </li>
          <li>
            <a href="#">Mobile</a>
          </li>
          <li>
            <a href="#">Tab</a>
          </li>
          <li>
            <a href="#">Web</a>
          </li>
          <li>
            <a href="#">Large web</a>
          </li>
        </ul>
      </div>
    </div></li>
  <li><div class="download-container">
      <div class="dropdown-container">
        <button type="button" name="button">Download</button>

        <ul class="template-options-dropdown">
          <li>
            <a href="#">Original</a>
          </li>
          <li>
            <a href="#">Thumb</a>
          </li>
          <li>
            <a href="#">Mobile</a>
          </li>
          <li>
            <a href="#">Tab</a>
          </li>
          <li>
            <a href="#">Web</a>
          </li>
          <li>
            <a href="#">Large web</a>
          </li>
        </ul>
      </div>
    </div></li>
  <li><div class="download-container">
      <div class="dropdown-container">
        <button type="button" name="button">Download</button>

        <ul class="template-options-dropdown">
          <li>
            <a href="#">Original</a>
          </li>
          <li>
            <a href="#">Thumb</a>
          </li>
          <li>
            <a href="#">Mobile</a>
          </li>
          <li>
            <a href="#">Tab</a>
          </li>
          <li>
            <a href="#">Web</a>
          </li>
          <li>
            <a href="#">Large web</a>
          </li>
        </ul>
      </div>
    </div></li>
  <li><div class="download-container">
      <div class="dropdown-container">
        <button type="button" name="button">Download</button>

        <ul class="template-options-dropdown">
          <li>
            <a href="#">Original</a>
          </li>
          <li>
            <a href="#">Thumb</a>
          </li>
          <li>
            <a href="#">Mobile</a>
          </li>
          <li>
            <a href="#">Tab</a>
          </li>
          <li>
            <a href="#">Web</a>
          </li>
          <li>
            <a href="#">Large web</a>
          </li>
        </ul>
      </div>
    </div></li>
  <li><div class="download-container">
      <div class="dropdown-container">
        <button type="button" name="button">Download</button>

        <ul class="template-options-dropdown">
          <li>
            <a href="#">Original</a>
          </li>
          <li>
            <a href="#">Thumb</a>
          </li>
          <li>
            <a href="#">Mobile</a>
          </li>
          <li>
            <a href="#">Tab</a>
          </li>
          <li>
            <a href="#">Web</a>
          </li>
          <li>
            <a href="#">Large web</a>
          </li>
        </ul>
      </div>
    </div></li>
</ul>

- JV Lobo

Answer 1

很遗憾，也许没有纯CSS的解决方案—CSS3过渡会创建一个新的堆叠上下文—请参阅相关文档描述和this thread获得另一种效果:

如果属性的值与none不同，则将创建一个堆叠上下文。

来源: MDN

您可以在那里轻松地用position:relative替换translate(0,0)，并为.template-options-dropdown添加一个大于零的z-index，以解决问题。

$(document).ready(function() {
  $('button[name="button"]').click(function(e) {
    $(e.currentTarget).parent().find('.template-options-dropdown').toggleClass('open');
  });
});

.boxes {
  list-style-type: none;
}

.boxes >li {
  float: left;
  width: 100px;
  height: 100px;
  background-color: red;
  margin: 5px;
  /*transform: translate(0, 0);*/
  position: relative; /*ADDED*/
}

.download-container {
  background: rgba(40, 39, 39, 0.8);
  bottom: 0;
  position: absolute;
  text-align: center;
  width: 100%;
}

.download-container .dropdown-container {
  display: inline-block;
  position: relative;
}

.download-container .dropdown-container button {
  background: #0bb9ab;
  color: #fff;
  padding: 6px 12px;
}

.template-options-dropdown {
  list-style-type: none;
  text-align: left;
  padding: 0;
  position: absolute;
  background-color: #111;
  visibility: hidden;
  z-index: 2;/*ADDED*/
}

.template-options-dropdown.open {
  visibility: visible;
}

.template-options-dropdown li a {
  color: white;
  text-decoration: none;
}

<script src="https://ajax.googleapis.com/ajax/libs/jquery/2.1.1/jquery.min.js"></script>
<ul class="boxes">
  <li>
    <div class="download-container">
      <div class="dropdown-container">
        <button type="button" name="button">Download</button>

        <ul class="template-options-dropdown">
          <li>
            <a href="#">Original</a>
          </li>
          <li>
            <a href="#">Thumb</a>
          </li>
          <li>
            <a href="#">Mobile</a>
          </li>
          <li>
            <a href="#">Tab</a>
          </li>
          <li>
            <a href="#">Web</a>
          </li>
          <li>
            <a href="#">Large web</a>
          </li>
        </ul>
      </div>
    </div>
  </li>
  <li><div class="download-container">
      <div class="dropdown-container">
        <button type="button" name="button">Download</button>

        <ul class="template-options-dropdown">
          <li>
            <a href="#">Original</a>
          </li>
          <li>
            <a href="#">Thumb</a>
          </li>
          <li>
            <a href="#">Mobile</a>
          </li>
          <li>
            <a href="#">Tab</a>
          </li>
          <li>
            <a href="#">Web</a>
          </li>
          <li>
            <a href="#">Large web</a>
          </li>
        </ul>
      </div>
    </div></li>
  <li><div class="download-container">
      <div class="dropdown-container">
        <button type="button" name="button">Download</button>

        <ul class="template-options-dropdown">
          <li>
            <a href="#">Original</a>
          </li>
          <li>
            <a href="#">Thumb</a>
          </li>
          <li>
            <a href="#">Mobile</a>
          </li>
          <li>
            <a href="#">Tab</a>
          </li>
          <li>
            <a href="#">Web</a>
          </li>
          <li>
            <a href="#">Large web</a>
          </li>
        </ul>
      </div>
    </div></li>
  <li><div class="download-container">
      <div class="dropdown-container">
        <button type="button" name="button">Download</button>

        <ul class="template-options-dropdown">
          <li>
            <a href="#">Original</a>
          </li>
          <li>
            <a href="#">Thumb</a>
          </li>
          <li>
            <a href="#">Mobile</a>
          </li>
          <li>
            <a href="#">Tab</a>
          </li>
          <li>
            <a href="#">Web</a>
          </li>
          <li>
            <a href="#">Large web</a>
          </li>
        </ul>
      </div>
    </div></li>
  <li><div class="download-container">
      <div class="dropdown-container">
        <button type="button" name="button">Download</button>

        <ul class="template-options-dropdown">
          <li>
            <a href="#">Original</a>
          </li>
          <li>
            <a href="#">Thumb</a>
          </li>
          <li>
            <a href="#">Mobile</a>
          </li>
          <li>
            <a href="#">Tab</a>
          </li>
          <li>
            <a href="#">Web</a>
          </li>
          <li>
            <a href="#">Large web</a>
          </li>
        </ul>
      </div>
    </div></li>
  <li><div class="download-container">
      <div class="dropdown-container">
        <button type="button" name="button">Download</button>

        <ul class="template-options-dropdown">
          <li>
            <a href="#">Original</a>
          </li>
          <li>
            <a href="#">Thumb</a>
          </li>
          <li>
            <a href="#">Mobile</a>
          </li>
          <li>
            <a href="#">Tab</a>
          </li>
          <li>
            <a href="#">Web</a>
          </li>
          <li>
            <a href="#">Large web</a>
          </li>
        </ul>
      </div>
    </div></li>
  <li><div class="download-container">
      <div class="dropdown-container">
        <button type="button" name="button">Download</button>

        <ul class="template-options-dropdown">
          <li>
            <a href="#">Original</a>
          </li>
          <li>
            <a href="#">Thumb</a>
          </li>
          <li>
            <a href="#">Mobile</a>
          </li>
          <li>
            <a href="#">Tab</a>
          </li>
          <li>
            <a href="#">Web</a>
          </li>
          <li>
            <a href="#">Large web</a>
          </li>
        </ul>
      </div>
    </div></li>
  <li><div class="download-container">
      <div class="dropdown-container">
        <button type="button" name="button">Download</button>

        <ul class="template-options-dropdown">
          <li>
            <a href="#">Original</a>
          </li>
          <li>
            <a href="#">Thumb</a>
          </li>
          <li>
            <a href="#">Mobile</a>
          </li>
          <li>
            <a href="#">Tab</a>
          </li>
          <li>
            <a href="#">Web</a>
          </li>
          <li>
            <a href="#">Large web</a>
          </li>
        </ul>
      </div>
    </div></li>
</ul>

一种笨拙的解决方案，会弄乱换行 - 你可以添加更多变换：

1. 为ul添加scaleY(-1)使列表倒序，因为具有更高索引的列表项将覆盖具有较低索引的列表项。

2. 对于li进行scaleY(-1)的反转操作，使世界回到正常状态。

3. 同时清除li的浮动。

请参见下面的演示：

$(document).ready(function() {
  $('button[name="button"]').click(function(e) {
    $(e.currentTarget).parent().find('.template-options-dropdown').toggleClass('open');
  });
});

.boxes {
  list-style-type: none;
  transform: scaleY(-1);/*ADDED*/
}
.boxes:after {/*ADDED*/
  content: '';
  clear: both;
  display: block;
}

.boxes >li {
  float: left;
  width: 100px;
  height: 100px;
  background-color: red;
  margin: 5px;
  transform: translate(0, 0) scaleY(-1);/*ADDED*/
}

.download-container {
  background: rgba(40, 39, 39, 0.8);
  bottom: 0;
  position: absolute;
  text-align: center;
  width: 100%;
}

.download-container .dropdown-container {
  display: inline-block;
  position: relative;
}

.download-container .dropdown-container button {
  background: #0bb9ab;
  color: #fff;
  padding: 6px 12px;
}

.template-options-dropdown {
  list-style-type: none;
  text-align: left;
  padding: 0;
  position: absolute;
  background-color: #111;
  visibility: hidden;
}

.template-options-dropdown.open {
  visibility: visible;
}

.template-options-dropdown li a {
  color: white;
  text-decoration: none;
}

<script src="https://ajax.googleapis.com/ajax/libs/jquery/2.1.1/jquery.min.js"></script>
<ul class="boxes">
  <li>
    <div class="download-container">
      <div class="dropdown-container">
        <button type="button" name="button">Download</button>

        <ul class="template-options-dropdown">
          <li>
            <a href="#">Original</a>
          </li>
          <li>
            <a href="#">Thumb</a>
          </li>
          <li>
            <a href="#">Mobile</a>
          </li>
          <li>
            <a href="#">Tab</a>
          </li>
          <li>
            <a href="#">Web</a>
          </li>
          <li>
            <a href="#">Large web</a>
          </li>
        </ul>
      </div>
    </div>
  </li>
  <li><div class="download-container">
      <div class="dropdown-container">
        <button type="button" name="button">Download</button>

        <ul class="template-options-dropdown">
          <li>
            <a href="#">Original</a>
          </li>
          <li>
            <a href="#">Thumb</a>
          </li>
          <li>
            <a href="#">Mobile</a>
          </li>
          <li>
            <a href="#">Tab</a>
          </li>
          <li>
            <a href="#">Web</a>
          </li>
          <li>
            <a href="#">Large web</a>
          </li>
        </ul>
      </div>
    </div></li>
  <li><div class="download-container">
      <div class="dropdown-container">
        <button type="button" name="button">Download</button>

        <ul class="template-options-dropdown">
          <li>
            <a href="#">Original</a>
          </li>
          <li>
            <a href="#">Thumb</a>
          </li>
          <li>
            <a href="#">Mobile</a>
          </li>
          <li>
            <a href="#">Tab</a>
          </li>
          <li>
            <a href="#">Web</a>
          </li>
          <li>
            <a href="#">Large web</a>
          </li>
        </ul>
      </div>
    </div></li>
  <li><div class="download-container">
      <div class="dropdown-container">
        <button type="button" name="button">Download</button>

        <ul class="template-options-dropdown">
          <li>
            <a href="#">Original</a>
          </li>
          <li>
            <a href="#">Thumb</a>
          </li>
          <li>
            <a href="#">Mobile</a>
          </li>
          <li>
            <a href="#">Tab</a>
          </li>
          <li>
            <a href="#">Web</a>
          </li>
          <li>
            <a href="#">Large web</a>
          </li>
        </ul>
      </div>
    </div></li>
  <li><div class="download-container">
      <div class="dropdown-container">
        <button type="button" name="button">Download</button>

        <ul class="template-options-dropdown">
          <li>
            <a href="#">Original</a>
          </li>
          <li>
            <a href="#">Thumb</a>
          </li>
          <li>
            <a href="#">Mobile</a>
          </li>
          <li>
            <a href="#">Tab</a>
          </li>
          <li>
            <a href="#">Web</a>
          </li>
          <li>
            <a href="#">Large web</a>
          </li>
        </ul>
      </div>
    </div></li>
  <li><div class="download-container">
      <div class="dropdown-container">
        <button type="button" name="button">Download</button>

        <ul class="template-options-dropdown">
          <li>
            <a href="#">Original</a>
          </li>
          <li>
            <a href="#">Thumb</a>
          </li>
          <li>
            <a href="#">Mobile</a>
          </li>
          <li>
            <a href="#">Tab</a>
          </li>
          <li>
            <a href="#">Web</a>
          </li>
          <li>
            <a href="#">Large web</a>
          </li>
        </ul>
      </div>
    </div></li>
  <li><div class="download-container">
      <div class="dropdown-container">
        <button type="button" name="button">Download</button>

        <ul class="template-options-dropdown">
          <li>
            <a href="#">Original</a>
          </li>
          <li>
            <a href="#">Thumb</a>
          </li>
          <li>
            <a href="#">Mobile</a>
          </li>
          <li>
            <a href="#">Tab</a>
          </li>
          <li>
            <a href="#">Web</a>
          </li>
          <li>
            <a href="#">Large web</a>
          </li>
        </ul>
      </div>
    </div></li>
  <li><div class="download-container">
      <div class="dropdown-container">
        <button type="button" name="button">Download</button>

        <ul class="template-options-dropdown">
          <li>
            <a href="#">Original</a>
          </li>
          <li>
            <a href="#">Thumb</a>
          </li>
          <li>
            <a href="#">Mobile</a>
          </li>
          <li>
            <a href="#">Tab</a>
          </li>
          <li>
            <a href="#">Web</a>
          </li>
          <li>
            <a href="#">Large web</a>
          </li>
        </ul>
      </div>
    </div></li>
</ul>

如果translate（0,0）仍无法删除，则除了使用JavaScript之外别无选择：

1. 通过将 z-index 赋值为列表中的索引来反转列表堆叠。

2. 在 li 中添加 position:relative

请参见下面的演示：

$(document).ready(function() {

  // ADDED
  $($('ul.boxes > li').get().reverse()).each(function(index){
     $(this).css('z-index', index);
  });

  $('button[name="button"]').click(function(e) {
    $(e.currentTarget).parent().find('.template-options-dropdown').toggleClass('open');
  });
});

.boxes {
  list-style-type: none;
}

.boxes >li {
  float: left;
  width: 100px;
  height: 100px;
  background-color: red;
  margin: 5px;
  transform: translate(0, 0);
  position: relative;/*ADDED*/
}

.download-container {
  background: rgba(40, 39, 39, 0.8);
  bottom: 0;
  position: absolute;
  text-align: center;
  width: 100%;
}

.download-container .dropdown-container {
  display: inline-block;
  position: relative;
}

.download-container .dropdown-container button {
  background: #0bb9ab;
  color: #fff;
  padding: 6px 12px;
}

.template-options-dropdown {
  list-style-type: none;
  text-align: left;
  padding: 0;
  position: absolute;
  background-color: #111;
  visibility: hidden;
}

.template-options-dropdown.open {
  visibility: visible;
}

.template-options-dropdown li a {
  color: white;
  text-decoration: none;
}

<script src="https://ajax.googleapis.com/ajax/libs/jquery/2.1.1/jquery.min.js"></script>
<ul class="boxes">
  <li>
    <div class="download-container">
      <div class="dropdown-container">
        <button type="button" name="button">Download</button>

        <ul class="template-options-dropdown">
          <li>
            <a href="#">Original</a>
          </li>
          <li>
            <a href="#">Thumb</a>
          </li>
          <li>
            <a href="#">Mobile</a>
          </li>
          <li>
            <a href="#">Tab</a>
          </li>
          <li>
            <a href="#">Web</a>
          </li>
          <li>
            <a href="#">Large web</a>
          </li>
        </ul>
      </div>
    </div>
  </li>
  <li><div class="download-container">
      <div class="dropdown-container">
        <button type="button" name="button">Download</button>

        <ul class="template-options-dropdown">
          <li>
            <a href="#">Original</a>
          </li>
          <li>
            <a href="#">Thumb</a>
          </li>
          <li>
            <a href="#">Mobile</a>
          </li>
          <li>
            <a href="#">Tab</a>
          </li>
          <li>
            <a href="#">Web</a>
          </li>
          <li>
            <a href="#">Large web</a>
          </li>
        </ul>
      </div>
    </div></li>
  <li><div class="download-container">
      <div class="dropdown-container">
        <button type="button" name="button">Download</button>

        <ul class="template-options-dropdown">
          <li>
            <a href="#">Original</a>
          </li>
          <li>
            <a href="#">Thumb</a>
          </li>
          <li>
            <a href="#">Mobile</a>
          </li>
          <li>
            <a href="#">Tab</a>
          </li>
          <li>
            <a href="#">Web</a>
          </li>
          <li>
            <a href="#">Large web</a>
          </li>
        </ul>
      </div>
    </div></li>
  <li><div class="download-container">
      <div class="dropdown-container">
        <button type="button" name="button">Download</button>

        <ul class="template-options-dropdown">
          <li>
            <a href="#">Original</a>
          </li>
          <li>
            <a href="#">Thumb</a>
          </li>
          <li>
            <a href="#">Mobile</a>
          </li>
          <li>
            <a href="#">Tab</a>
          </li>
          <li>
            <a href="#">Web</a>
          </li>
          <li>
            <a href="#">Large web</a>
          </li>
        </ul>
      </div>
    </div></li>
  <li><div class="download-container">
      <div class="dropdown-container">
        <button type="button" name="button">Download</button>

        <ul class="template-options-dropdown">
          <li>
            <a href="#">Original</a>
          </li>
          <li>
            <a href="#">Thumb</a>
          </li>
          <li>
            <a href="#">Mobile</a>
          </li>
          <li>
            <a href="#">Tab</a>
          </li>
          <li>
            <a href="#">Web</a>
          </li>
          <li>
            <a href="#">Large web</a>
          </li>
        </ul>
      </div>
    </div></li>
  <li><div class="download-container">
      <div class="dropdown-container">
        <button type="button" name="button">Download</button>

        <ul class="template-options-dropdown">
          <li>
            <a href="#">Original</a>
          </li>
          <li>
            <a href="#">Thumb</a>
          </li>
          <li>
            <a href="#">Mobile</a>
          </li>
          <li>
            <a href="#">Tab</a>
          </li>
          <li>
            <a href="#">Web</a>
          </li>
          <li>
            <a href="#">Large web</a>
          </li>
        </ul>
      </div>
    </div></li>
  <li><div class="download-container">
      <div class="dropdown-container">
        <button type="button" name="button">Download</button>

        <ul class="template-options-dropdown">
          <li>
            <a href="#">Original</a>
          </li>
          <li>
            <a href="#">Thumb</a>
          </li>
          <li>
            <a href="#">Mobile</a>
          </li>
          <li>
            <a href="#">Tab</a>
          </li>
          <li>
            <a href="#">Web</a>
          </li>
          <li>
            <a href="#">Large web</a>
          </li>
        </ul>
      </div>
    </div></li>
  <li><div class="download-container">
      <div class="dropdown-container">
        <button type="button" name="button">Download</button>

        <ul class="template-options-dropdown">
          <li>
            <a href="#">Original</a>
          </li>
          <li>
            <a href="#">Thumb</a>
          </li>
          <li>
            <a href="#">Mobile</a>
          </li>
          <li>
            <a href="#">Tab</a>
          </li>
          <li>
            <a href="#">Web</a>
          </li>
          <li>
            <a href="#">Large web</a>
          </li>
        </ul>
      </div>
    </div></li>
</ul>

- kukkuz

Answer 2

z-index 只能作用于定位属性为 absolute、fixed 或 relative 的元素。因此，请在 li 元素上应用 position: relative。

对于固定数量的元素，您可以尝试

.boxes li:nth-child(1) {
  z-index: 8;
}

.boxes li:nth-child(2) {
  z-index: 7;
}

.boxes li:nth-child(3) {
  z-index: 6;
}

.boxes li:nth-child(4) {
  z-index: 5;
}

.boxes li:nth-child(5) {
  z-index: 4;
}

.boxes li:nth-child(6) {
  z-index: 3;
}

.boxes li:nth-child(7) {
  z-index: 2;
}

.boxes li:nth-child(8) {
  z-index: 1;
}

如果元素数量未知，您可以使用脚本动态应用它。

$(document).ready(function() {
  $('button[name="button"]').click(function(e) {
    $(e.currentTarget).parent().find('.template-options-dropdown').toggleClass('open');
  });
});

.boxes {
  list-style-type: none;
}

.boxes >li {
  float: left;
  width: 100px;
  height: 100px;
  background-color: red;
  margin: 5px;
  transform: translate(0, 0);
  position: relative;
}

.download-container {
  background: rgba(40, 39, 39, 0.8);
  bottom: 0;
  position: absolute;
  text-align: center;
  width: 100%;
}

.download-container .dropdown-container {
  display: inline-block;
  position: relative;
}

.download-container .dropdown-container button {
  background: #0bb9ab;
  color: #fff;
  padding: 6px 12px;
}

.template-options-dropdown {
  list-style-type: none;
  text-align: left;
  padding: 0;
  position: absolute;
  background-color: #111;
  visibility: hidden;
}

.template-options-dropdown.open {
  visibility: visible;
}

.template-options-dropdown li a {
  color: white;
  text-decoration: none;
}

.boxes li:nth-child(1) {
  z-index: 8;
}

.boxes li:nth-child(2) {
  z-index: 7;
}

.boxes li:nth-child(3) {
  z-index: 6;
}

.boxes li:nth-child(4) {
  z-index: 5;
}

.boxes li:nth-child(5) {
  z-index: 4;
}

.boxes li:nth-child(6) {
  z-index: 3;
}

.boxes li:nth-child(7) {
  z-index: 2;
}

.boxes li:nth-child(8) {
  z-index: 1;
}

<script src="https://ajax.googleapis.com/ajax/libs/jquery/2.1.1/jquery.min.js"></script>
<ul class="boxes">
  <li>
    <div class="download-container">
      <div class="dropdown-container">
        <button type="button" name="button">Download</button>

        <ul class="template-options-dropdown">
          <li>
            <a href="#">Original</a>
          </li>
          <li>
            <a href="#">Thumb</a>
          </li>
          <li>
            <a href="#">Mobile</a>
          </li>
          <li>
            <a href="#">Tab</a>
          </li>
          <li>
            <a href="#">Web</a>
          </li>
          <li>
            <a href="#">Large web</a>
          </li>
        </ul>
      </div>
    </div>
  </li>
  <li><div class="download-container">
      <div class="dropdown-container">
        <button type="button" name="button">Download</button>

        <ul class="template-options-dropdown">
          <li>
            <a href="#">Original</a>
          </li>
          <li>
            <a href="#">Thumb</a>
          </li>
          <li>
            <a href="#">Mobile</a>
          </li>
          <li>
            <a href="#">Tab</a>
          </li>
          <li>
            <a href="#">Web</a>
          </li>
          <li>
            <a href="#">Large web</a>
          </li>
        </ul>
      </div>
    </div></li>
  <li><div class="download-container">
      <div class="dropdown-container">
        <button type="button" name="button">Download</button>

        <ul class="template-options-dropdown">
          <li>
            <a href="#">Original</a>
          </li>
          <li>
            <a href="#">Thumb</a>
          </li>
          <li>
            <a href="#">Mobile</a>
          </li>
          <li>
            <a href="#">Tab</a>
          </li>
          <li>
            <a href="#">Web</a>
          </li>
          <li>
            <a href="#">Large web</a>
          </li>
        </ul>
      </div>
    </div></li>
  <li><div class="download-container">
      <div class="dropdown-container">
        <button type="button" name="button">Download</button>

        <ul class="template-options-dropdown">
          <li>
            <a href="#">Original</a>
          </li>
          <li>
            <a href="#">Thumb</a>
          </li>
          <li>
            <a href="#">Mobile</a>
          </li>
          <li>
            <a href="#">Tab</a>
          </li>
          <li>
            <a href="#">Web</a>
          </li>
          <li>
            <a href="#">Large web</a>
          </li>
        </ul>
      </div>
    </div></li>
  <li><div class="download-container">
      <div class="dropdown-container">
        <button type="button" name="button">Download</button>

        <ul class="template-options-dropdown">
          <li>
            <a href="#">Original</a>
          </li>
          <li>
            <a href="#">Thumb</a>
          </li>
          <li>
            <a href="#">Mobile</a>
          </li>
          <li>
            <a href="#">Tab</a>
          </li>
          <li>
            <a href="#">Web</a>
          </li>
          <li>
            <a href="#">Large web</a>
          </li>
        </ul>
      </div>
    </div></li>
  <li><div class="download-container">
      <div class="dropdown-container">
        <button type="button" name="button">Download</button>

        <ul class="template-options-dropdown">
          <li>
            <a href="#">Original</a>
          </li>
          <li>
            <a href="#">Thumb</a>
          </li>
          <li>
            <a href="#">Mobile</a>
          </li>
          <li>
            <a href="#">Tab</a>
          </li>
          <li>
            <a href="#">Web</a>
          </li>
          <li>
            <a href="#">Large web</a>
          </li>
        </ul>
      </div>
    </div></li>
  <li><div class="download-container">
      <div class="dropdown-container">
        <button type="button" name="button">Download</button>

        <ul class="template-options-dropdown">
          <li>
            <a href="#">Original</a>
          </li>
          <li>
            <a href="#">Thumb</a>
          </li>
          <li>
            <a href="#">Mobile</a>
          </li>
          <li>
            <a href="#">Tab</a>
          </li>
          <li>
            <a href="#">Web</a>
          </li>
          <li>
            <a href="#">Large web</a>
          </li>
        </ul>
      </div>
    </div></li>
  <li><div class="download-container">
      <div class="dropdown-container">
        <button type="button" name="button">Download</button>

        <ul class="template-options-dropdown">
          <li>
            <a href="#">Original</a>
          </li>
          <li>
            <a href="#">Thumb</a>
          </li>
          <li>
            <a href="#">Mobile</a>
          </li>
          <li>
            <a href="#">Tab</a>
          </li>
          <li>
            <a href="#">Web</a>
          </li>
          <li>
            <a href="#">Large web</a>
          </li>
        </ul>
      </div>
    </div></li>
</ul>

- user4447799

---

谢谢你的回答，Anurag。问题是那些li可能多了或少了，所以...在这种情况下，那个解决方案不好。 - undefined

就像我在答案中提到的那样，对于未知数量的元素，你可以使用脚本动态地应用样式。 - user4447799

是的，抱歉。我试图只用CSS找到一个解决方案 :) 谢谢！ - undefined

Answer 3

你已经接近成功了，但如果是我，我会在<li>或div.download-container上设置.open类，并使用大量的z-index来打开子菜单。我们还必须在我们设置z-index的元素上设置position:relative;，否则z-index不起作用。

示例：

$(document).ready(function() {
  $('button[name="button"]').click(function(e) {
    $(e.currentTarget).parents('li').toggleClass('open');
  });
});

.boxes {
  list-style-type: none;
}

.boxes >li {
  float: left;
  width: 100px;
  height: 100px;
  background-color: red;
  margin: 5px;
  transform: translate(0, 0);
  position:relative;
}

.boxes >li.open {
    z-index:500;
}

.download-container {
  background: rgba(40, 39, 39, 0.8);
  bottom: 0;
  position: absolute;
  text-align: center;
  width: 100%;
}

.download-container .dropdown-container {
  display: inline-block;
  position: relative;
}

.download-container .dropdown-container button {
  background: #0bb9ab;
  color: #fff;
  padding: 6px 12px;
}

.template-options-dropdown {
  list-style-type: none;
  text-align: left;
  padding: 0;
  position: absolute;
  background-color: #111;
  visibility: hidden;
}

.boxes li.open .template-options-dropdown {
  visibility: visible;
}

.template-options-dropdown li a {
  color: white;
  text-decoration: none;
}

<script src="https://ajax.googleapis.com/ajax/libs/jquery/2.1.1/jquery.min.js"></script>
<ul class="boxes">
  <li>
    <div class="download-container">
      <div class="dropdown-container">
        <button type="button" name="button">Download</button>

        <ul class="template-options-dropdown">
          <li>
            <a href="#">Original</a>
          </li>
          <li>
            <a href="#">Thumb</a>
          </li>
          <li>
            <a href="#">Mobile</a>
          </li>
          <li>
            <a href="#">Tab</a>
          </li>
          <li>
            <a href="#">Web</a>
          </li>
          <li>
            <a href="#">Large web</a>
          </li>
        </ul>
      </div>
    </div>
  </li>
  <li><div class="download-container">
      <div class="dropdown-container">
        <button type="button" name="button">Download</button>

        <ul class="template-options-dropdown">
          <li>
            <a href="#">Original</a>
          </li>
          <li>
            <a href="#">Thumb</a>
          </li>
          <li>
            <a href="#">Mobile</a>
          </li>
          <li>
            <a href="#">Tab</a>
          </li>
          <li>
            <a href="#">Web</a>
          </li>
          <li>
            <a href="#">Large web</a>
          </li>
        </ul>
      </div>
    </div></li>
  <li><div class="download-container">
      <div class="dropdown-container">
        <button type="button" name="button">Download</button>

        <ul class="template-options-dropdown">
          <li>
            <a href="#">Original</a>
          </li>
          <li>
            <a href="#">Thumb</a>
          </li>
          <li>
            <a href="#">Mobile</a>
          </li>
          <li>
            <a href="#">Tab</a>
          </li>
          <li>
            <a href="#">Web</a>
          </li>
          <li>
            <a href="#">Large web</a>
          </li>
        </ul>
      </div>
    </div></li>
  <li><div class="download-container">
      <div class="dropdown-container">
        <button type="button" name="button">Download</button>

        <ul class="template-options-dropdown">
          <li>
            <a href="#">Original</a>
          </li>
          <li>
            <a href="#">Thumb</a>
          </li>
          <li>
            <a href="#">Mobile</a>
          </li>
          <li>
            <a href="#">Tab</a>
          </li>
          <li>
            <a href="#">Web</a>
          </li>
          <li>
            <a href="#">Large web</a>
          </li>
        </ul>
      </div>
    </div></li>
  <li><div class="download-container">
      <div class="dropdown-container">
        <button type="button" name="button">Download</button>

        <ul class="template-options-dropdown">
          <li>
            <a href="#">Original</a>
          </li>
          <li>
            <a href="#">Thumb</a>
          </li>
          <li>
            <a href="#">Mobile</a>
          </li>
          <li>
            <a href="#">Tab</a>
          </li>
          <li>
            <a href="#">Web</a>
          </li>
          <li>
            <a href="#">Large web</a>
          </li>
        </ul>
      </div>
    </div></li>
  <li><div class="download-container">
      <div class="dropdown-container">
        <button type="button" name="button">Download</button>

        <ul class="template-options-dropdown">
          <li>
            <a href="#">Original</a>
          </li>
          <li>
            <a href="#">Thumb</a>
          </li>
          <li>
            <a href="#">Mobile</a>
          </li>
          <li>
            <a href="#">Tab</a>
          </li>
          <li>
            <a href="#">Web</a>
          </li>
          <li>
            <a href="#">Large web</a>
          </li>
        </ul>
      </div>
    </div></li>
  <li><div class="download-container">
      <div class="dropdown-container">
        <button type="button" name="button">Download</button>

        <ul class="template-options-dropdown">
          <li>
            <a href="#">Original</a>
          </li>
          <li>
            <a href="#">Thumb</a>
          </li>
          <li>
            <a href="#">Mobile</a>
          </li>
          <li>
            <a href="#">Tab</a>
          </li>
          <li>
            <a href="#">Web</a>
          </li>
          <li>
            <a href="#">Large web</a>
          </li>
        </ul>
      </div>
    </div></li>
  <li><div class="download-container">
      <div class="dropdown-container">
        <button type="button" name="button">Download</button>

        <ul class="template-options-dropdown">
          <li>
            <a href="#">Original</a>
          </li>
          <li>
            <a href="#">Thumb</a>
          </li>
          <li>
            <a href="#">Mobile</a>
          </li>
          <li>
            <a href="#">Tab</a>
          </li>
          <li>
            <a href="#">Web</a>
          </li>
          <li>
            <a href="#">Large web</a>
          </li>
        </ul>
      </div>
    </div></li>
</ul>

- John B