Question

display:block;不适用于最大宽度：320像素。

背景变为绿色，但是<li>始终显示为浮动：

.parent-ul li {
    display: block;
    height: 32px;
    width: 15.7%;
/*    float: left;*/
}

* {
    margin: 0;
    padding: 0;
    box-sizing: border-box;
}

body {
    background: royalblue;
    font-family: monospace;  
}

header {
    position: relative;
    top: 0px;
    margin: 0 auto;
    height: 38px;
    width: 100%;
    padding-top: 2px;
    background: red;
}
.parent-ul {
    position: relative;
    list-style: none;
    text-align: center;
    margin-left: 16%;
}

.parent-ul li {
    height: 32px;
    width: 15.7%;
    float: left;
}

.parent-ul li{
    border-left: 1px solid silver;
}

#prod {
    border-right: 1px solid silver;
}

.parent-ul a {
    text-decoration: none;
    color: white;
    padding: 12px 38px;
    font-size: 15px;
    transition: color 1s, font-size .5s;
    line-height: 32px;
}

/* 398px ================================= */

@media screen and (max-width: 320px) {
    
body {
    background: green;
}

header {
    position: relative;
    top: 0px;
    margin: 0 auto;
/*    height: 38px;*/
    width: 100%;
    padding-top: 2px;
    background: red;
}
.parent-ul {
    position: relative;
    list-style: none;
    text-align: center;
    margin-left: 16%;
}

.parent-ul li {
    display: block;
    height: 32px;
    width: 15.7%;
/*    float: left;*/
}

.parent-ul li{
    border-left: 1px solid silver;
}

#prod {
    border-right: 1px solid silver;
}

.parent-ul a {
    text-decoration: none;
    color: white;
    padding: 12px 38px;
    font-size: 15px;
    transition: color 1s, font-size .5s;
    line-height: 32px;
}
}

<body>   
     <header>
       <ul class="parent-ul">
        
            <li><a href="homepage.html">Home</a></li>
            <li><a href="#">Services</a></li>
            <li><a href="#">Products</a></li>
            <li><a href="#">Contact</a></li>
            <li id="prod"><a href="index.html">About&nbsp;Us</a></li>
            
        </ul>      
     </header>
</body>

Answer 1

无论何时使用float，都要清除它。在您的情况下，您在Web中使用了float，但尚未在320媒体查询中清除它，请使用float清除它：none;清除：两者；

显示：块；对@media没有影响（最大宽度：320像素）

1 个答案: