我正在练习响应式网页设计，并使用 flex。
问题是，当屏幕小于 768px 时，我想让 .menu li 的宽度为 100%，所以我尝试给 .menu ul 和 .menu li width: 100%。但它不起作用。我也试过 flex: 0 0 100% 但没有任何反应。
如何使 .menu li 100%？
* {
box-sizing: border-box;
}
nav ul,
.outline ul {
list-style-type: none;
margin: 0;
padding: 0;
}
/*common*/
/*layout*/
.container {
max-width: 900px;
margin: 0;
}
.outline {
flex: 2;
}
section {
flex: 7;
}
/*header*/
header {
display: flex;
}
.login ul,
.menu ul {
display: flex;
}
.login ul {
justify-content: flex-end;
}
.toparea {
margin-left: auto;
}
/*section*/
.contents {
display: flex;
}
/*media query*/
@media only screen and (max-width: 768px) {
body {
background-color: #EAC0F0;
}
header {
flex-direction: column;
}
.logo {
justify-content: center;
}
.login {
display: none;
}
.menu ul {
flex-direction: column;
}
.contents {
flex-direction: column;
}
.outline ul {
display: flex;
}
.outline li {
flex: 1;
}
}
/*footer*/
/*temp*/
img,
.login ul,
.menu ul,
.outline li {
border: 1px solid black;
}<!DOCTYPE html>
<html lang="en">
<head>
<meta charset="UTF-8">
<meta name="viewport" content="width=device-width, initial-scale=1.0">
<meta http-equiv="X-UA-Compatible" content="ie=edge">
<title>RWD</title>
<link rel="stylesheet" href="./rwd.css">
</head>
<body>
<div class="container">
<header>
<img src="" alt="logo">
<div class="toparea">
<nav class="login">
<ul>
<li>Login</li>
<li>Help</li>
</ul>
</nav>
<nav class="menu">
<ul>
<li>Menu1</li>
<li>Menu2</li>
<li>Menu3</li>
<li>Menu4</li>
</ul>
</nav>
</div>
</header>
<div class="contents">
<div class="outline">
<ul>
<li>Outline1-1</li>
<li>Outline1-2</li>
</ul>
</div>
<section>
<h1>heading</h1>
<p>paragraph</p>
</section>
</div>
<footer>
<address>Contact : email@email.com</address>
</footer>
</div>
</body>
</html>最佳答案
这里的主要问题是 toparea 规则中的 margin-left: auto
如果你想保持元素垂直堆叠，你可以像这样更新你的媒体查询，并重置边距 margin-left: 0
@media only screen and (max-width: 768px ) {
body { background-color: #EAC0F0; }
header { flex-direction: column; }
.logo { justify-content: center; }
.login { display: none; }
.menu ul { flex-direction: column; }
.contents { flex-direction: column; }
.outline ul { display: flex; }
.outline li { flex: 1; }
.toparea { margin-left: 0; } /* added */
}
堆栈片段
* { box-sizing: border-box; }
nav ul, .outline ul { list-style-type: none; margin: 0; padding: 0; }
/*common*/
/*layout*/
.container { max-width: 900px; margin: 0; }
.outline { flex: 2; }
section { flex: 7; }
/*header*/
header { display: flex; }
.login ul, .menu ul { display: flex; }
.login ul { justify-content: flex-end; }
.toparea { margin-left: auto; }
/*section*/
.contents { display: flex; }
/*media query*/
@media only screen and (max-width: 768px ) {
body { background-color: #EAC0F0; }
header { flex-direction: column; }
.logo { justify-content: center; }
.login { display: none; }
.menu ul { flex-direction: column; }
.contents { flex-direction: column; }
.outline ul { display: flex; }
.outline li { flex: 1; }
.toparea { margin-left: 0; } /* added */
}
/*footer*/
/*temp*/
img, .login ul, .menu ul, .outline li { border: 1px solid black; }<header>
<img src="" alt="logo">
<div class="toparea">
<nav class="login">
<ul>
<li>Login</li>
<li>Help</li>
</ul>
</nav>
<nav class="menu">
<ul>
<li>Menu1</li>
<li>Menu2</li>
<li>Menu3</li>
<li>Menu4</li>
</ul>
</nav>
</div>
</header>
<div class="contents">
<div class="outline">
<ul>
<li>Outline1-1</li>
<li>Outline1-2</li>
</ul>
</div>
<section>
<h1>heading</h1>
<p>paragraph</p>
</section>
</div>
<footer>
<address>Contact : email@email.com</address>
</footer>
</div>如果你想让它们水平堆叠，你可以像这样更新你的媒体查询，让 li 增长
@media only screen and (max-width: 768px ) {
body { background-color: #EAC0F0; }
header { flex-direction: column; }
.logo { justify-content: center; }
.login { display: none; }
.menu li { flex-grow: 1; } /* changed */
.contents { flex-direction: column; }
.outline ul { display: flex; }
.outline li { flex: 1; }
.toparea { margin-left: 0; } /* added */
}
堆栈片段
* { box-sizing: border-box; }
nav ul, .outline ul { list-style-type: none; margin: 0; padding: 0; }
/*common*/
/*layout*/
.container { max-width: 900px; margin: 0; }
.outline { flex: 2; }
section { flex: 7; }
/*header*/
header { display: flex; }
.login ul, .menu ul { display: flex; }
.login ul { justify-content: flex-end; }
.toparea { margin-left: auto; }
/*section*/
.contents { display: flex; }
/*media query*/
@media only screen and (max-width: 768px ) {
body { background-color: #EAC0F0; }
header { flex-direction: column; }
.logo { justify-content: center; }
.login { display: none; }
.menu li { flex-grow: 1; }
.contents { flex-direction: column; }
.outline ul { display: flex; }
.outline li { flex: 1; }
.toparea { margin-left: 0; }
}
/*footer*/
/*temp*/
img, .login ul, .menu ul, .outline li { border: 1px solid black; }<header>
<img src="" alt="logo">
<div class="toparea">
<nav class="login">
<ul>
<li>Login</li>
<li>Help</li>
</ul>
</nav>
<nav class="menu">
<ul>
<li>Menu1</li>
<li>Menu2</li>
<li>Menu3</li>
<li>Menu4</li>
</ul>
</nav>
</div>
</header>
<div class="contents">
<div class="outline">
<ul>
<li>Outline1-1</li>
<li>Outline1-2</li>
</ul>
</div>
<section>
<h1>heading</h1>
<p>paragraph</p>
</section>
</div>
<footer>
<address>Contact : email@email.com</address>
</footer>
</div>关于html - 我如何给 flex 元素 100% 宽度？，我们在Stack Overflow上找到一个类似的问题： https://stackoverflow.com/questions/46362559/