html - 固定高度 div 内的 Bootstrap 下拉菜单

Question

我在固定高度的 div 中有一个 Bootstrap 下拉菜单，其中包含可滚动的内容 (overflow-y: scroll;)。我的问题是，当菜单的高度变长时，它会隐藏在其父 div 内，因为它具有垂直滚动条。我想以全尺寸显示它(在其父级上方)。 z-index 不适用于此。

.highlights-box {
  background-color: #f5f5f5;
  border: 1px solid #e0e0e0;
  font-size: 17px;
  font-family: camberia;
  padding-left: 0px;
  padding-right: 0px;
  margin-top: 7px;
}

.highlights-box h1 {
  font-family: camberia;
  text-align: center;
  padding-top: 10px;
  padding-bottom: 10px;
  font-size: 24px;
  font-weight: normal;
}

.unesco {
  padding-top: 2px;
  padding-bottom: 2px;
  border-top: 1px solid #e0e0e0;
  border-bottom: 1px solid #e0e0e0;
  padding-left: 20px;
  font-size: 18px;
}

.city-heading {
  font-weight: bold;
  text-decoration: underline;
  text-align: center;
  padding-top: 7px;
  padding-bottom: 7px;
  text-transform: uppercase;
}

.monuments {
  height: 200px;
  overflow-y: scroll;
  padding-left: 10px;
  padding-right: 10px;
}

.monuments li {
  list-style: none;
  padding: 10px;
  padding-bottom: 10px;
  border-bottom: 1px solid #e0e0e0;
}

.highlights-box .dropdown-menu {
  top: 66%;
  left: 100px;
  z-index:9999;
}
.dropdown:hover .dropdown-menu {
    display: block;
}

.dropdown-menu li {
  padding: 0px;
}

.dropdown-menu li a:hover {
  font-size: 15px;
}

<link href="https://maxcdn.bootstrapcdn.com/bootstrap/3.3.7/css/bootstrap.min.css" rel="stylesheet"/>
<div class="col-md-6 col-sm-6 col-xs-12 highlights-box">
  <h1>Tour Highlights</h1>
  <div class="unesco" style="border-bottom:none; padding-top:8px; padding-bottom:5px;">U = UNESCO World Heritage Site</div>
  <div class="unesco" style="border-top:none; padding-bottom:8px">E = Unique Experience</div>
  <div class="monuments" id="monuments">
    <div class="city-heading">
      <a id="Delhi"></a>
      <div class="city-heading dropdown dropdown-toggle"><span onclick="scrollDiv('Delhi',jQuery(this))">Delhi</span><span class="caret"></span>
        <ul class="dropdown-menu">
          <li onclick="scrollDiv('Varanasi',jQuery(this))"><a href="javascript:void(0)">Varanasi</a></li>
          <li onclick="scrollDiv('Agra',jQuery(this))"><a href="javascript:void(0)">Agra</a></li>
          <li onclick="scrollDiv('Abhaneri (Enroute)',jQuery(this))"><a href="javascript:void(0)">Abhaneri (Enroute)</a></li>
          <li onclick="scrollDiv('Ranthambore',jQuery(this))"><a href="javascript:void(0)">Ranthambore</a></li>
          <li onclick="scrollDiv('Jaipur',jQuery(this))"><a href="javascript:void(0)">Jaipur</a></li>
          <li onclick="scrollDiv('Ranakpur',jQuery(this))"><a href="javascript:void(0)">Ranakpur</a></li>
          <li onclick="scrollDiv('Udaipur',jQuery(this))"><a href="javascript:void(0)">Udaipur</a></li>
          <li onclick="scrollDiv('Mumbai',jQuery(this))"><a href="javascript:void(0)">Mumbai</a></li>
          <li onclick="scrollDiv('Aurangabad',jQuery(this))"><a href="javascript:void(0)">Aurangabad</a></li>
          <li onclick="scrollDiv('Cochin',jQuery(this))"><a href="javascript:void(0)">Cochin</a></li>
          <li onclick="scrollDiv('Backwaters',jQuery(this))"><a href="javascript:void(0)">Backwaters</a></li>
        </ul>
      </div>
    </div>
    <li>Qutab Minar - U</li>
    <li>Guided walk through ancient spice bazaar in Chandni Chowk - E</li>
    <li>Red Fort - U</li>
    <li>Rickshaw Ride in Old Delhi's Crowded Bazaar - E</li>
    <li>India Gate</li>
    <li>National Museum</li>
    <li>Humayun's Tomb - U</li>
    <li>Bangla Sahib Gurudwara - E</li>
    <li>Jama Masjid</li>

    <div class="city-heading">
      <a id="Varanasi"></a>Varanasi</div>
    <li>Sunset Arti prayer ceremony on the holy river - E</li>
    <li>Sunrise and Sunset boat cruises on the holy river - E</li>
    <li>Sarnath Archaelogical Museum*</li>

    <div class="city-heading">
      <a id="Agra"></a>Agra</div>
    <li>Agra Fort - U</li>
    <li>Taj Mahal (Both sunrise and sunset visits) - U</li>

    <div class="city-heading">
      <a id="Abhaneri (Enroute)"></a>Abhaneri (Enroute)</div>
    <li>Rajasthani Village Walk - E</li>
    <li>Chand Baori Stepwell</li>

    <div class="city-heading">
      <a id="Ranthambore"></a>Ranthambore</div>
    <li>Wildlife Safaris</li>
    <li>Ranthambore Fort</li>

    <div class="city-heading">
      <a id="Jaipur"></a>Jaipur</div>
    <li>Amber Fort and Palace - U</li>
    <li>Jantar Mantar - U</li>
    <li>City Palace</li>
    <li>Hawa Mahal (Palace of the Winds)</li>
    <li>Monkey Temple - E</li>
    <li>Elephant Ride to Amer Fort - E</li>
    <li>Camelback (or Camel cart) safari at Samode - E</li>
    <li>Rajasthani Lunch at Samode Palace</li>

    <div class="city-heading">
      <a id="Ranakpur"></a>Ranakpur</div>
    <li>15th Century Jain Temple</li>
    <li>Purebred Marwari Horse Ride - E</li>

    <div class="city-heading">
      <a id="Udaipur"></a>Udaipur</div>
    <li>City Palace</li>
    <li>Crystal Gallery</li>
    <li>Monsoon Palace Excursion - E</li>
    <li>Boat Cruise on Lake Pichola</li>
    <li>Three Wheeler (Tuk Tuk) ride through the streets of Udaipur - E</li>

    <div class="city-heading">
      <a id="Mumbai"></a>Mumbai</div>
    <li>The Gateway Of India</li>
    <li>Prince of Wales Museum</li>
    <li>The Victoria Terminus - U</li>
    <li>Drive on the Queen's Necklace (Marine Drive)</li>
    <li>Historic Flora Fountain and Fort area exploration</li>
    <li>Mumbai's Launderers - Old Traditional Dhobi Ghats - E</li>

    <div class="city-heading">
      <a id="Aurangabad"></a>Aurangabad</div>
    <li>Ajanta Caves - U</li>
    <li>Ellora Caves - U</li>

    <div class="city-heading">
      <a id="Cochin"></a>Cochin</div>
    <li>Cherai Island - E</li>
    <li>15th Century Synangogue</li>
    <li>St. Francis Church</li>
    <li>Chinese Fishing Nets</li>
    <li>Fort Kochi historic architecture</li>
    <li>Kathakali Dance Performance</li>
    <li>Dinner and cooking lesson with a famous Keralan chef - E</li>

    <div class="city-heading">
      <a id="Backwaters"></a>Backwaters</div>
    <li>Cruise through the idyllic backwaters - E</li>

  </div>
</div>

这里是 fiddle

Answer 1

问题是因为当 position:absolute 元素在同时具有 position:relative 和 overflow:hidden 或 scroll 的父级内部时，它们将被他们的 parent 裁剪。

解决方案是在两个父级别上分别设置这些样式:将 position: relative 设置为绝对元素的直接父级，但设置 overflow(滚动或隐藏) 在祖 parent 元素上!如以下模式:

<div class="grand-parent">  => position: relative;  
  <div class="parent">      => overflow: hidden; (or scroll;)  
    <div class="child">     => position: absolute; 
    </div>
  </div>
</div>

对于您的情况，我们可以使用现有元素来实现。

• 将 position:relative 添加到 .highlights-box div 中作为我们的祖 parent 。

• overflow-y: scroll 设置在 .monuments div 上。这充当中间 parent 。

• 然后我们通过修改 .city-heading 类来覆盖 .dropdown 的 position:relative 使得 .city -heading 是正常(静态)位置元素。

样式变化如下:

.highlights-box {
  ...
  position: relative; /* !!EDIT!! ensure pos:relative of grand-parent */
}

.city-heading {
  ...
  position: static; /* override position:relative of .dropdown */
}

.highlights-box .dropdown-menu {
  top: 53%; /* better position than 66% */
  ...
}

这里是 updated fiddle.