悬停时悬停菜单会向上移动

Question

当鼠标悬停在drop2 div中的链接上时，整个drop2 div会向上移动几个像素。与drop3相同的问题。

当我将鼠标悬停在div上时，为什么div会向上移动？谢谢，任何建议非常感谢。

#nav {
  background-color: #373737;
  float: left;
  height: 30px;
  padding: 0px 0px 0px 0px;
  width: 970px;
}
.nav a {
  display: block;
}
.nav ul li a {
  position: relative;
}
a {
  text-decoration: none;
}
a.item {
  color: white;
}
.item {
  position: relative;
}
a.item:hover {
  background-color: #dcd0c0;
  height: 30px;
  color: #373737;
  font-weight: bold;
}
.menu {
  list-style-type: none;
  margin: auto;
  width: 970px;
  text-align: center;
}
.nav .items {
  display: inline;
  float: left;
  margin: 0px 100px 0px 100px;
  padding: 0;
  text-align: center;
  width: 82px;
}
.drop2 {
  display: none;
  text-align: left;
  width: 150px;
  padding-left: 10px;
  padding-top: 5px;
  padding-bottom: 5px;
}
.items:hover .drop2 {
  display: block;
  width: 150px;
  padding-left: 10px;
  padding-top: 5px;
  padding-bottom: 5px;
  background-color: #f4f4f4;
  position: relative;
  z-index: 99;
}
.drop3 {
  display: none;
  text-align: left;
  padding-left: 10px;
  padding-top: 5px;
  padding-bottom: 5px;
  width: 150px;
}
.items:hover .drop3 {
  display: block;
  width: 150px;
  padding-left: 10px;
  padding-top: 5px;
  padding-bottom: 5px;
  background-color: #f4f4f4;
  position: relative;
  z-index: 99;
}
.drop2 > a {
  color: #373737;
}
.drop3 > a {
  color: #373737;
}
.drop2 > a:hover {
  font-weight: bold;
}
.drop3 > a:hover {
  font-weight: bold;
}

<div id="nav">
  <div class="nav">
    <ul class="menu">
      <li class="items">
        <a href="#" class="item">Photos</a>
      </li>
      <li class="items">
        <a href="#" class="item">Locations</a>
        <div class="drop2">
          <a href="#">Bays</a>
          <a href="#">Lakes</a>
          <a href="#">Pacific Ocean</a>
        </div>
      </li>
      <li class="items">
        <a href="#" class="item">Catches</a>
        <div class="drop3">
          <a href="#">Bass</a>
          <a href="#">Other</a>
        </div>
      </li>
    </ul>
  </div>
</div>

Answer 1

将line-height: 30px;添加到css中的#nav标记。

jsfiddle