尝试创建带有菜单下拉列表的导航栏，但我的菜单项似乎不想出现或它们隐藏在我的父容器中

Question

我正在创建一个简单的导航栏，我想让它做出响应。我目前的问题是我正在尝试在其中一个菜单项上有一个下拉菜单(从 W3Schools 中提取(，当我悬停时，没有任何项目出现，但当我检查它们时它们会显示。

我尝试应用 z 索引并将位置更改为相对位置，但没有任何工作正常。

   <div class="navwrap">
      <div class="topnav" id="myTopnav">
         <a href="#home" class="active">Home</a>
         <a href="#news">News</a>
         <a href="#contact">Contact</a>
         <a href="#about">About</a>
         <a href="javascript:void(0);" class="icon" onclick="myFunction()">
            <i class="fa fa-bars"></i>
         </a>
         <div class="dropdown">
            <button class="dropbtn">Dropdown</button>
            <div class="dropdown-content">
               <a href="#">Link 1</a>
               <a href="#">Link 2</a>
               <a href="#">Link 3</a>
            </div>
         </div>
      </div>
   </div>

.CSS

.navwrap{}
.topnav {
   overflow: hidden;
   background-color: #333;
   .dropdown {
      button.dropbtn {
      }
      .dropdown-content {}
   }
   .dropdown:hover .dropdown-content {
      display: block;
   }
 }
 .topnav a {
   float: left;
   display: block;
   color: #f2f2f2;
   text-align: center;
   padding: 14px 16px;
   text-decoration: none;
   font-size: 17px;
 }
 .topnav a:hover {
   background-color: #ddd;
   color: black;
 }
 .active {
   background-color: #4CAF50;
   color: white;
 }
 .topnav .icon {
   display: none;
 }
 @media screen and (max-width: 600px) {
   .topnav a:not(:first-child) {display: none;}
   .topnav a.icon {
     float: right;
     display: block;
   }
 }
 @media screen and (max-width: 600px) {
   .topnav.responsive {position: relative;}
   .topnav.responsive .icon {
     position: absolute;
     right: 0;
     top: 0;
   }
   .topnav.responsive a {
     float: none;
     display: block;
     text-align: left;
   }
 }
//Navigation Dropdown
.dropbtn {
   background-color: #4CAF50;
   color: white;
   padding: 16px;
   font-size: 16px;
   border: none;
}
.dropdown {
   position: relative;
   display: inline-block;
}
.dropdown-content {
   display: none;
   position: absolute;
   background-color: #f1f1f1;
   min-width: 160px;
   box-shadow: 0px 8px 16px 0px rgba(0, 0, 0, 0.2);
   z-index: 1;
}
.dropdown-content a {
   color: black;
   padding: 12px 16px;
   text-decoration: none;
   display: block;
}
.dropdown-content a:hover {
   background-color: #ddd;
}
.dropdown:hover .dropdown-content {
   display: block;
}
.dropdown:hover .dropbtn {
   background-color: #3e8e41;
}

JAVASCRIPT

function myFunction() {
    var x = document.getElementById("myTopnav");
    if (x.className === "topnav") {
      x.className += " responsive";
    } else {
      x.className = "topnav";
    }
  }

应该有带有我的"下拉菜单"菜单项的导航栏和一个下拉菜单。

function myFunction() {
  var x = document.getElementById("myTopnav");
  if (x.className === "topnav") {
    x.className += " responsive";
  } else {
    x.className = "topnav";
  }
}

.navwrap {}
.topnav {
  overflow: hidden;
  background-color: #333;
  .dropdown {
    button.dropbtn {}
    .dropdown-content {}
  }
  .dropdown:hover .dropdown-content {
    display: block;
  }
}
.topnav a {
  float: left;
  display: block;
  color: #f2f2f2;
  text-align: center;
  padding: 14px 16px;
  text-decoration: none;
  font-size: 17px;
}
.topnav a:hover {
  background-color: #ddd;
  color: black;
}
.active {
  background-color: #4CAF50;
  color: white;
}
.topnav .icon {
  display: none;
}
@media screen and (max-width: 600px) {
  .topnav a:not(:first-child) {
    display: none;
  }
  .topnav a.icon {
    float: right;
    display: block;
  }
}
@media screen and (max-width: 600px) {
  .topnav.responsive {
    position: relative;
  }
  .topnav.responsive .icon {
    position: absolute;
    right: 0;
    top: 0;
  }
  .topnav.responsive a {
    float: none;
    display: block;
    text-align: left;
  }
}
//Navigation Dropdown
.dropbtn {
  background-color: #4CAF50;
  color: white;
  padding: 16px;
  font-size: 16px;
  border: none;
}
.dropdown {
  position: relative;
  display: inline-block;
}
.dropdown-content {
  display: none;
  position: absolute;
  background-color: #f1f1f1;
  min-width: 160px;
  box-shadow: 0px 8px 16px 0px rgba(0, 0, 0, 0.2);
  z-index: 1;
}
.dropdown-content a {
  color: black;
  padding: 12px 16px;
  text-decoration: none;
  display: block;
}
.dropdown-content a:hover {
  background-color: #ddd;
}
.dropdown:hover .dropdown-content {
  display: block;
}
.dropdown:hover .dropbtn {
  background-color: #3e8e41;
}

<!-- NAVIGATION -->
<div class="navwrap">
  <div class="topnav" id="myTopnav">
    <a href="#home" class="active">Home</a>
    <a href="#news">News</a>
    <a href="#contact">Contact</a>
    <a href="#about">About</a>
    <a href="javascript:void(0);" class="icon" onclick="myFunction()">
      <i class="fa fa-bars"></i>
    </a>
    <div class="dropdown">
      <button class="dropbtn">Dropdown</button>
      <div class="dropdown-content">
        <a href="#">Link 1</a>
        <a href="#">Link 2</a>
        <a href="#">Link 3</a>
      </div>
    </div>
  </div>
</div>

Answer 1

overflow: hidden需要visible