必应自动建议下拉菜单响应式CSS

以下是一个使用CSS实现必应自动建议下拉菜单的解决方法示例：

HTML代码：

<input type="text" id="search-box" placeholder="Search">

<div id="suggestions-container">
  <ul id="suggestions-list">
    <!-- Suggestions will be dynamically added here -->
  </ul>
</div>

CSS代码：

#suggestions-container {
  position: relative;
  display: inline-block;
}

#suggestions-list {
  list-style-type: none;
  padding: 0;
  margin: 0;
  background-color: #f9f9f9;
  border: 1px solid #ddd;
  border-top: none;
  position: absolute;
  width: 100%;
  z-index: 999;
  display: none;
}

#suggestions-list li {
  padding: 10px;
  cursor: pointer;
}

#suggestions-list li:hover {
  background-color: #e9e9e9;
}

#search-box:focus + #suggestions-container #suggestions-list {
  display: block;
}

JavaScript代码：

const searchBox = document.getElementById("search-box");
const suggestionsList = document.getElementById("suggestions-list");

searchBox.addEventListener("input", function() {
  // Fetch suggestions based on the input value
  const suggestions = fetchSuggestions(this.value);

  // Clear previous suggestions
  suggestionsList.innerHTML = "";

  // Append new suggestions to the list
  suggestions.forEach(function(suggestion) {
    const li = document.createElement("li");
    li.textContent = suggestion;
    suggestionsList.appendChild(li);
  });
});

suggestionsList.addEventListener("click", function(event) {
  // Set the selected suggestion as the input value
  searchBox.value = event.target.textContent;

  // Clear suggestions
  suggestionsList.innerHTML = "";
});

function fetchSuggestions(input) {
  // Fetch suggestions from an API or any other data source
  // Return an array of suggestions based on the input value
  // For demonstration purposes, returning a static array
  return ["Suggestion 1", "Suggestion 2", "Suggestion 3"];
}

该解决方法使用了CSS的相邻兄弟选择器（+）来根据输入框的焦点状态显示或隐藏建议列表。当输入框获得焦点时，建议列表显示，失去焦点时隐藏。

JavaScript部分包括了一个事件监听器，监听输入框的输入事件。每当输入框的值发生变化时，会触发该事件处理函数。在该函数中，可以调用一个自定义函数fetchSuggestions来获取建议列表，并将建议添加到#suggestions-list中。

点击建议列表中的选项时，会将选中的建议设置为输入框的值，并清空建议列表。

根据实际需求，你可以根据自己的API或数据源来获取建议列表，并对CSS样式进行自定义。