下拉菜单不起作用？

Question

我已在这段代码中搜索过会导致其无法运行的错误，但似乎找不到任何错误。一切都很好，除了菜单不会下拉。有没有人有任何提示？

这是我的代码片段：

ul {
  list-style-type: none;
  margin: 0;
  padding: 0;
  overflow: hidden;
  background-color: #5BC8C3;
  position: fixed;
  top: 60px;
  width: 100%;
}
li {
  float: left;
}
li a,
.dropbtn {
  display: inline-block;
  color: #f7f7f7;
  text-align: center;
  padding: 14px 16px;
  text-decoration: none;
}
li a:hover,
.dropdown:hover .dropbtn {
  background-color: #F7f7f7;
}
li.dropdown {
  display: inline-block;
}
.dropdown-content {
  display: none;
  position: absolute;
  background-color: #284A64;
  min-width: 160px;
  box-shadow: 0px 8px 16px 0px rgba(0, 0, 0, 0.2);
}
.dropdown-content a {
  color: #f7f7f7;
  padding: 12px 16px;
  text-decoration: none;
  display: block;
  text-align: left;
}
.dropdown-content a:hover {
  background-color: #f7f7f7
}
.dropdown:hover .dropdown-content {
  display: block;
}

<ul>
  <li><a class="active" href="#index">Home</a>
  </li>
  <li><a href="#catalog">Catalog</a>
  </li>
  <li><a href="#calendar">Calendar</a>
  </li>
  <li class="dropdown">
    <a href="#" class="dropbtn">Library Information</a>
    <div class="dropdown-content">
      <a href="#childrensprogram">Children's Programs</a>
      <a href="#adultprograming">Adult Programs</a>
      <a href="#help">Help Services</a>
      <a href="#otherserv">Other Services</a>
      <a href="#policy">Library Policies</a>
    </div>
  </li>
  <li><a href="#contact">Contact</a>
  </li>
</ul>

感谢您的宝贵意见！

Answer 1

好吧，下拉菜单实际上出现了:)

但是我们看不到，因为你的菜单是

overflow: hidden;

如果您删除此 css 行，您的菜单将起作用：

ul {
  list-style-type: none;
  margin: 0;
  padding: 0;
  background-color: #5BC8C3;
  position: fixed;
  top: 60px;
  width: 100%;
}
li {
  float: left;
}
li a,
.dropbtn {
  display: inline-block;
  color: #f7f7f7;
  text-align: center;
  padding: 14px 16px;
  text-decoration: none;
}
li a:hover,
.dropdown:hover .dropbtn {
  background-color: #F7f7f7;
}
li.dropdown {
  display: inline-block;
}
.dropdown-content {
  display: none;
  position: absolute;
  background-color: #284A64;
  min-width: 160px;
  box-shadow: 0px 8px 16px 0px rgba(0, 0, 0, 0.2);
}
.dropdown-content a {
  color: #f7f7f7;
  padding: 12px 16px;
  text-decoration: none;
  display: block;
  text-align: left;
}
.dropdown-content a:hover {
  background-color: #f7f7f7
}
.dropdown:hover .dropdown-content {
  display: block;
}

<ul>
  <li><a class="active" href="#index">Home</a>
  </li>
  <li><a href="#catalog">Catalog</a>
  </li>
  <li><a href="#calendar">Calendar</a>
  </li>
  <li class="dropdown">
    <a href="#" class="dropbtn">Library Information</a>
    <div class="dropdown-content">
      <a href="#childrensprogram">Children's Programs</a>
      <a href="#adultprograming">Adult Programs</a>
      <a href="#help">Help Services</a>
      <a href="#otherserv">Other Services</a>
      <a href="#policy">Library Policies</a>
    </div>
  </li>
  <li><a href="#contact">Contact</a>
  </li>
</ul>

Answer 2

ul{
    margin:0px;
    padding:0px; 
    list-style:none;

    }

ul li{
    background-color:#5BC8C3;
    width:150px;
    height:50px;
    float:left;
    line-height:50px;
    color:#0FC;
    text-align:center;
        }
ul li a{
    color: #FFF;
    text-decoration:none;
    display:block;
    }           
ul li a:hover{
    background-color:#F7f7f7;
    }

<ul>
    <li><a href="#">Home</a></li>
    <li><a href="#">Catalog</a></li>
    <li><a href="#">Calender</a></li>
    <li><a href="#">Library Information</a>
    <ul>
      <li><a href="#">Children's Programs</a></li>
      <li><a href="#">Adult Programs</a></li>
      <li><a href="#">Help Services</a></li>
    </ul>
    </li>
    <li><a href="#">Contact</a></li>
 </ul>

下拉菜单不起作用？

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