以this示例为起点，我试图创建一个导航栏，该导航栏的左侧和右侧部分均垂直，以确保其中所有元素在垂直方向上居中。不幸的是，即使right-aligned和left-aligned类都设置了vertical-align: middle属性，其右侧也没有垂直居中。我缺少什么？这是代码串：
<html>
<style>
header img {
display: inline-block;
}
header nav {
display: inline-block;
font-size: 1em;
vertical-align: middle;
}
header nav ul {
padding: 0;
margin: 0;
}
header nav ul img {
vertical-align: middle;
}
header nav li {
display: inline-block;
}
header nav li a {
display: inline-block;
padding: .4em .8em;
font-size: 1em;
text-decoration: none;
color: black;
background: #eee;
line-height: 1;
}
header .container {
max-width: 800px;
margin: auto;
overflow: hidden;
}
.left-aligned {
float: left;
}
.right-aligned {
float: right;
}
</style>
<body>
<header role="banner">
<div class="container">
<div class="left-aligned">
<img class="left" src="http://placehold.it/200x200">
</div>
<div class="right-aligned">
<nav id="navigation" role="navigation">
<ul>
<li>
<img src="http://placehold.it/100x100">
<a href="#" title="About Us">About Us</a>
</li>
<li><a href="#" title="Biographies">Biographies</a></li>
<li><a href="#" title="Services">Services</a></li>
<li><a href="#" title="Careers">Careers</a></li>
<li><a href="#" title="Contact">Contact</a></li>
</ul>
</nav>
</div>
</div>
</header>
</body>
</html>
这是flex的好用例-通过在容器类中添加以下三行，可以实现左右对齐的部分：
display: flex;
justify-content: space-between;
align-items: center;
因此您的最终代码将如下所示（为了清楚起见，我将HTML和CSS分开了：]
header img {
display: inline-block;
}
header nav {
display: inline-block;
font-size: 1em;
}
header nav ul {
padding: 0;
margin: 0;
}
header nav ul img {
vertical-align: middle;
}
header nav li {
display: inline-block;
}
header nav li a {
display: inline-block;
padding: .4em .8em;
font-size: 1em;
text-decoration: none;
color: black;
background: #eee;
line-height: 1;
}
header .container {
max-width: 800px;
margin: auto;
overflow: hidden;
display: flex;
justify-content: space-between;
align-items: center;
}<header role="banner">
<div class="container">
<div class="left-aligned">
<img class="left" src="http://placehold.it/200x200">
</div>
<div class="right-aligned">
<nav id="navigation" role="navigation">
<ul>
<li>
<img src="http://placehold.it/100x100">
<a href="#" title="About Us">About Us</a>
</li>
<li><a href="#" title="Biographies">Biographies</a></li>
<li><a href="#" title="Services">Services</a></li>
<li><a href="#" title="Careers">Careers</a></li>
<li><a href="#" title="Contact">Contact</a></li>
</ul>
</nav>
</div>
</div>
</header>