如何使下拉菜单内容水平居中和全宽

<div class="dropdown">
  <button class="dropbtn">下拉菜单</button>
  <div class="dropdown-content">
    <a href="#">菜单项1</a>
    <a href="#">菜单项2</a>
    <a href="#">菜单项3</a>
  </div>
</div>

.dropdown {
  position: relative;
  display: inline-block;
}

.dropbtn {
  background-color: #f1f1f1;
  color: #333;
  padding: 10px;
  border: none;
  cursor: pointer;
}

.dropdown-content {
  position: absolute;
  left: 50%;
  transform: translateX(-50%);
  width: 100%;
  background-color: #f9f9f9;
  padding: 10px;
  display: none;
}

.dropdown-content a {
  color: #333;
  display: block;
  padding: 5px;
  text-decoration: none;
}

.dropdown:hover .dropdown-content {
  display: block;
}