How to use the flex layout of CSS3 to achieve the adaptive effect of the web navigation bar?

How to use the flex layout of CSS3 to achieve the adaptive effect of the web navigation bar?

In web design, the navigation bar is a very important component. It not only helps users quickly locate various pages of the website, but also improves user experience and page aesthetics. However, due to the existence of different screen sizes, the adaptability of the navigation bar becomes a design problem. Fortunately, CSS3's flex layout provides us with a simple and flexible solution.

First of all, in the HTML structure, we can use an unordered list <ul></ul> to create the navigation bar. Each navigation item can be wrapped using <li> elements. For example:

<nav>
  <ul>
    <li>首页</li>
    <li>产品</li>
    <li>服务</li>
    <li>关于我们</li>
    <li>联系我们</li>
  </ul>
</nav>

Next, we need to set the style for the navigation bar in CSS and use flex layout to achieve adaptive effects. First, we need to set the outer container <nav> of the navigation bar as follows:

nav {
  display: flex; /* 声明为flex布局 */
  justify-content: space-between; /* 导航项均匀分布在水平空间中 */
  align-items: center; /* 导航项在垂直中心对齐 */
  background-color: #f1f1f1; /* 设置背景色 */
  padding: 16px; /* 设置内边距 */
}

Next, we need to set the navigation item <li> Style:

li {
  list-style-type: none; /* 去除默认的数字标记 */
  margin: 0 8px; /* 设置导航项之间的空隙 */
}

Now, we have completed the basic settings of the navigation bar. On small screen devices, all navigation items will be arranged vertically, while on large screen devices, the navigation items will be arranged horizontally. Next, we will use media queries (@media) to achieve the adaptive effect of the navigation bar:

@media screen and (max-width: 600px) {
  nav {
    flex-direction: column; /* 将导航项垂直排列 */
    justify-content: flex-start; /* 导航项从顶部开始对齐 */
    padding: 8px; /* 适当减少内边距 */
  }
  
  li {
    margin: 8px 0; /* 设置导航项之间的垂直空隙 */
  }
}

Through the above code, when the screen width is less than or equal to 600px, the navigation items will be arranged vertically , and align from the top.

Using the flex layout of CSS3, we have realized the adaptive effect of the web navigation bar. Whether on a large or small screen device, the navigation bar adjusts to the screen size to provide a better user experience.

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