无法在css的下拉菜单中获取全宽度

<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;
}

.dropdown-content {
  position: absolute;
  left: 0;
  right: 0;
  margin: 0;
  width: 100%;
  background-color: #f9f9f9;
  display: none;
}

.dropdown-content a {
  color: black;
  padding: 12px 16px;
  text-decoration: none;
  display: block;
}

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