固定了打开菜单时的底部div

Question

打开菜单时，我试图将class="overlay-bottom"的DIV设置在屏幕底部。但是，它甚至在菜单打开之前就已显示。我该怎么办？

function openNav() {
  document.getElementById("myNav").style.width = "100%";
}

function closeNav() {
  document.getElementById("myNav").style.width = "0%";
}

.overlay {
  height: 100%;
  width: 0;
  position: fixed;
  z-index: 1;
  top: 0;
  left: 0;
  background-color: rgb(0,0,0);
  background-color: rgba(0,0,0, 0.9);
  overflow-x: hidden;
  transition: 0.5s;
}

.overlay-content {
  position: relative;
  top: 25%;
  width: 100%;
  text-align: center;
  margin-top: 30px;
}

.overlay a {
  padding: 8px;
  text-decoration: none;
  font-size: 36px;
  color: #818181;
  display: block;
  transition: 0.3s;
}

.overlay a:hover, .overlay a:focus {
  color: #f1f1f1;
}

.overlay .closebtn {
  position: absolute;
  top: 20px;
  right: 45px;
  font-size: 60px;
}

@media screen and (max-height: 450px) {
  .overlay a {font-size: 20px}
  .overlay .closebtn {
  font-size: 40px;
  top: 15px;
  right: 35px;
  }
}
.overlay-bottom {
  position: fixed;
  bottom: 0;
  background-color: #e22727;
  width: 100%;
  color: #fff;
}

<div id="myNav" class="overlay">
  <a href="javascript:void(0)" class="closebtn" onclick="closeNav()">&times;</a>
  <div class="overlay-content">
    <a href="#">About</a>
    <a href="#">Services</a>
    <a href="#">Clients</a>
    <a href="#">Contact</a>
  </div>
  <div class="overlay-bottom">
    Bottom
  </div>
</div>
<span style="font-size:30px;cursor:pointer" onclick="openNav()">&#9776; open</span>

Answer 1

这就是您要寻找的，对吧？

function openNav() {
  document.getElementById("myNav").style.width = "100%";
  document.getElementsByClassName("overlay-bottom")[0].style.visibility = "visible";
}

function closeNav() {
  document.getElementById("myNav").style.width = "0%";
  document.getElementsByClassName("overlay-bottom")[0].style.visibility = "hidden";

}

.overlay {
  height: 100%;
  width: 0;
  position: fixed;
  z-index: 1;
  top: 0;
  left: 0;
  background-color: rgb(0, 0, 0);
  background-color: rgba(0, 0, 0, 0.9);
  overflow-x: hidden;
  transition: 0.5s;
}

.overlay-content {
  position: relative;
  top: 25%;
  width: 100%;
  text-align: center;
  margin-top: 30px;
}

.overlay a {
  padding: 8px;
  text-decoration: none;
  font-size: 36px;
  color: #818181;
  display: block;
  transition: 0.3s;
}

.overlay a:hover,
.overlay a:focus {
  color: #f1f1f1;
}

.overlay .closebtn {
  position: absolute;
  top: 20px;
  right: 45px;
  font-size: 60px;
}

@media screen and (max-height: 450px) {
  .overlay a {
    font-size: 20px
  }
  .overlay .closebtn {
    font-size: 40px;
    top: 15px;
    right: 35px;
  }
}

.overlay-bottom {
  position: fixed;
  bottom: 0;
  background-color: #e22727;
  width: 100%;
  color: #fff;
  visibility: hidden;
}

<div id="myNav" class="overlay">
  <a href="javascript:void(0)" class="closebtn" onclick="closeNav()">&times;</a>
  <div class="overlay-content">
    <a href="#">About</a>
    <a href="#">Services</a>
    <a href="#">Clients</a>
    <a href="#">Contact</a>
  </div>
</div>
<div class="overlay-bottom">
  Bottom
</div>
<span style="font-size:30px;cursor:pointer" onclick="openNav()">&#9776; open</span>