HTML 下拉框向下移动 html 个元素

Question

所以我试图让下拉列表在展开时与下面的元素重叠。不幸的是，即使相同堆叠上下文中的元素有一个位置，并且下拉容器 div 设置为 2 的 z-index，问题仍然存在；它不会重叠下面的元素，而是将它们向下移动。我还尝试通过向各种元素添加不透明度属性来改变堆叠上下文，但这也没有用。代码如下：

#firstone {
  z-index: 2;
}

#contain {
  height: 400px;
  width: 400px;
  background-color: rgba(100, 25, 25, 0.2);
}

body {
  text-align: center;
}

input:focus {
  outline: none;
}

.fancy_input_box {
  text-align: left;
  display: inline-block;
  margin: 40px 3% 1px;
  position: relative;
}

.fancy_input {
  font: 15px/24px "Lato", Arial, sans-serif;
  color: #aaa;
  box-sizing: border-box;
  letter-spacing: 1px;
  border: 0;
  padding: 7px 7px;
  border: 1px solid #ccc;
  position: relative;
  background: transparent;
}

.fancy_input:focus~.dropdown-content {
  display: block;
  cursor: default;
}

.fancy_input:focus~.dropdown-content>span {
  display: block;
  cursor: default;
}

.dropdown-content {
  display: none;
  background-color: rgba(0, 0, 0, 0.2);
  width: 222px;
  overflow: auto;
  position: relative;
}

.dropdown-content:active {
  display: block;
}

.dropdown-content>span {
  padding: 12px 16px;
  display: none;
}

.dropdown-content>span:hover {
  background-color: rgba(0, 0, 0, 0.1);
}

.fancy_input~.fancy_label {
  position: absolute;
  left: 14px;
  width: 100%;
  top: 10px;
  color: #aaa;
  letter-spacing: 0.5px;
  transition: 0.3s;
  -webkit-transition: 0.3s;
  -moz-transition: 0.3s;
  z-index: -1;
}

.fancy_input:focus~.fancy_label {
  top: -18px;
  left: 1px;
  font-size: 12px;
  color: grey !important;
  transition: 0.3s;
  -webkit-transition: 0.3s;
  -moz-transition: 0.3s;
}

.fancy_input:focus {
  border: 1px solid grey !important;
}

.fancy_input:not(focus):valid~.fancy_label {
  top: -18px;
  font-size: 12px;
  left: 1px;
  color: #aaa;
  transition: 0.3s;
  -webkit-transition: 0.3s;
  -moz-transition: 0.3s;
}

<!DOCTYPE html>
<html lang="en">

<head>
  <link rel="stylesheet" href="test.css">
</head>

<body>
  <div id="contain">

    <div id="firstone" class="fancy_input_box">
      <input class="fancy_input" type="text" placeholder="" maxlength="25" size="25" required>
      <label class="fancy_label">Search</label>

      <div class="dropdown-content">
        <span>a</span>
        <span>b</span>
        <span>c</span>
        <span>d</span>
        <span>e</span>
      </div>
    </div>

    <div class="fancy_input_box">
      <input class="fancy_input" type="text" placeholder="" maxlength="4" size="10">
      <label class="fancy_label">Thing</label>
    </div>

    <br>

    <div>
      <div class="fancy_input_box">
        <input class="fancy_input" type="text" placeholder="" maxlength="4" size="10">
        <label class="fancy_label">stuff</label>
      </div>

      <div class="fancy_input_box">
        <input class="fancy_input" type="text" placeholder="" maxlength="4" size="10">
        <label class="fancy_label">more stuff</label>
      </div>

      <div class="fancy_input_box">
        <input class="fancy_input" type="text" placeholder="" maxlength="4" size="10">
        <label class="fancy_label">more stuff</label>
      </div>
    </div>

  </div>
</body>

</html>

Answer 1

您的下拉内容应该是绝对定位的。

更新您的下拉样式，如下所示：

.dropdown-content {
  display: none;
  background-color: rgba(0, 0, 0, 0.2);
  width: 222px;
  overflow: auto;
  position: absolute;
  left: 0;
  top: 100%;
}

Answer 2

尝试使用以下代码设置绝对位置。我也将下拉内容中的宽度更改为 100% div 以获得良好的设计。

#firstone {
  z-index: 2;
}

#contain {
  height: 400px;
  width: 400px;
  background-color: rgba(100, 25, 25, 0.2);
}

body {
  text-align: center;
}

input:focus {
  outline: none;
}

.fancy_input_box {
  text-align: left;
  display: inline-block;
  margin: 40px 3% 1px;
  position: relative;
}

.fancy_input {
  font: 15px/24px "Lato", Arial, sans-serif;
  color: #aaa;
  box-sizing: border-box;
  letter-spacing: 1px;
  border: 0;
  padding: 7px 7px;
  border: 1px solid #ccc;
  position: relative;
  background: transparent;
}

.fancy_input:focus~.dropdown-content {
  display: block;
  cursor: default;
}

.fancy_input:focus~.dropdown-content>span {
  display: block;
  cursor: default;
}

.dropdown-content {
  display: none;
  background-color: rgba(0, 0, 0, 0.2);
  width: 100%;
  overflow: auto;
  position: absolute;
  
}

.dropdown-content:active {
  display: block;
}

.dropdown-content>span {
  padding: 12px 16px;
  display: none;
}

.dropdown-content>span:hover {
  background-color: rgba(0, 0, 0, 0.1);
}

.fancy_input~.fancy_label {
  position: absolute;
  left: 14px;
  width: 100%;
  top: 10px;
  color: #aaa;
  letter-spacing: 0.5px;
  transition: 0.3s;
  -webkit-transition: 0.3s;
  -moz-transition: 0.3s;
  z-index: -1;
}

.fancy_input:focus~.fancy_label {
  top: -18px;
  left: 1px;
  font-size: 12px;
  color: grey !important;
  transition: 0.3s;
  -webkit-transition: 0.3s;
  -moz-transition: 0.3s;
}

.fancy_input:focus {
  border: 1px solid grey !important;
}

.fancy_input:not(focus):valid~.fancy_label {
  top: -18px;
  font-size: 12px;
  left: 1px;
  color: #aaa;
  transition: 0.3s;
  -webkit-transition: 0.3s;
  -moz-transition: 0.3s;
}

<div id="contain">

    <div id="firstone" class="fancy_input_box">
      <input class="fancy_input" type="text" placeholder="" maxlength="25" size="25" required>
      <label class="fancy_label">Search</label>

      <div class="dropdown-content">
        <span>a</span>
        <span>b</span>
        <span>c</span>
        <span>d</span>
        <span>e</span>
      </div>
    </div>

    <div class="fancy_input_box">
      <input class="fancy_input" type="text" placeholder="" maxlength="4" size="10">
      <label class="fancy_label">Thing</label>
    </div>

    <br>

    <div>
      <div class="fancy_input_box">
        <input class="fancy_input" type="text" placeholder="" maxlength="4" size="10">
        <label class="fancy_label">stuff</label>
      </div>

      <div class="fancy_input_box">
        <input class="fancy_input" type="text" placeholder="" maxlength="4" size="10">
        <label class="fancy_label">more stuff</label>
      </div>

      <div class="fancy_input_box">
        <input class="fancy_input" type="text" placeholder="" maxlength="4" size="10">
        <label class="fancy_label">more stuff</label>
      </div>
    </div>

  </div>

Answer 3

只需添加 position:absolute 和 top:100%; 在您的下拉内容 class

jsfiddle from your code

  .dropdown-content {
  display: none;
  background-color: rgba(0, 0, 0, 0.2);
  width: 222px;
  overflow: auto;
  position: absolute;
  left: 0;
  top: 100%;
  }

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