我想让导航栏粘在视口的顶部一旦用户滚动页面，但它不工作，我不知道为什么。如果你可以帮助，这是我的HTML和CSS代码:
.container {
min-height: 300vh;
}
.nav-selections {
text-transform: uppercase;
letter-spacing: 5px;
font: 18px "lato",sans-serif;
display: inline-block;
text-decoration: none;
color: white;
padding: 18px;
float: right;
margin-left: 50px;
transition: 1.5s;
}
.nav-selections:hover{
transition: 1.5s;
color: black;
}
ul {
background-color: #B79b58;
overflow: auto;
}
li {
list-style-type: none;
}
<main class="container">
<nav style="position: sticky; position: -webkit-sticky;">
<ul align="left">
<li><a href="#/contact" class="nav-selections" style="margin-right:35px;">Contact</a></li>
<li><a href="#/about" class="nav-selections">About</a></li>
<li><a href="#/products" class="nav-selections">Products</a></li>
<li><a href="#" class="nav-selections">Home</a></li>
</ul>
</nav>
</main>
粘性定位是相对定位和固定定位的混合体。元素被视为相对定位，直到它超过指定的阈值，此时它被视为固定定位。
.．.
您必须指定一个阈值，其中至少有一个是上、右、下或左，以便粘滞定位按预期的方式工作。否则，它将与相对定位难以区分。
(来源:中数)
在你的例子中，你必须通过使用top属性来定义它最后应该停留的位置。
html, body {
height: 200%;
}
nav {
position: sticky;
position: -webkit-sticky;
top: 0; /* required */
}
.nav-selections {
text-transform: uppercase;
letter-spacing: 5px;
font: 18px "lato", sans-serif;
display: inline-block;
text-decoration: none;
color: white;
padding: 18px;
float: right;
margin-left: 50px;
transition: 1.5s;
}
.nav-selections:hover {
transition: 1.5s;
color: black;
}
ul {
background-color: #B79b58;
overflow: auto;
}
li {
list-style-type: none;
}
<nav>
<ul align="left">
<li><a href="#/contact" class="nav-selections" style="margin-right:35px;">Contact</a></li>
<li><a href="#/about" class="nav-selections">About</a></li>
<li><a href="#/products" class="nav-selections">Products</a></li>
<li><a href="#" class="nav-selections">Home</a></li>
</ul>
</nav>
我还遇到了一些事情:
当你的sticky元素是一个组件时(angular等)
如果“sticky”元素本身是一个带有自定义元素选择器的组件，比如一个名为<app-menu-bar>的angular组件，你需要在该组件的css中添加以下内容:
:主机{显示:块;} //或使用flexbox
or
app-menu-bar { display: block; } // (in the containing component's css)
Safari on iOS in particular seems to require `display:block` even on the root element `app-root` of an angular application or it won't stick.
If you are creating a component and defining the css inside the component (shadow DOM / encapsulated styles), make sure the position: sticky is being applied to the 'outer' selector (eg. app-menu-bar in devtools should show the sticky position) and not a top level div within the component. With Angular, this can be achieved with the :host selector in the css for your component.
:host
{
position: sticky;
display: block; // this is the same as shown above
top: 0;
background: red;
}
其他
If the element following your sticky element has a solid background, you must add the following to stop it from sliding underneath:
.sticky-element { z-index: 100; }
.parent-of-sticky-element { position: relative; }
Your sticky element must be before your content if using top and after it if using bottom.
There are complications when using overflow: hidden on your wrapper element – in general it will kill the sticky element inside. Better explained in this question
Mobile browsers may disable sticky/fixed positioned items when the onscreen keyboard is visible. I'm not sure of the exact rules (does anybody ever know) but when the keyboard is visible you're looking at a sort of 'window' into the window and you won't easily be able to get things to stick to the actual visible top of the screen.
Make sure you have:
position: sticky;
and not
display: sticky;
杂项可用性问题
Be cautious if your design calls for for sticking things to the bottom of the screen on mobile devices. On iPhone X for instance they display a narrow line to indicate the swipe region (to get back to the homepage) - and elements inside this region aren't clickable. So if you stick something there be sure to test on iPhone X that users can activate it. A big 'Buy Now' button is no good if people can't click it!
If you're advertising on Facebook the webpage is displayed in a 'webview' control within Facebook's mobile apps. Especially when displaying video (where your content begins in the bottom half of the screen only) - they often completely mess up sticky elements by putting your page within a scrollable viewport that actually allows your sticky elements to disappear off the top of the page. Be sure to test in the context of an actual ad and not just in the phone's browser or even Facebook's browser which can all behave differently.
我使用了JS解决方案。它适用于Firefox和Chrome浏览器。有任何问题，请告诉我。
html
<body>
<header id="header">
<h1>Extra-Long Page Heading That Wraps</h1>
<nav id="nav">
<ul>
<li><a href="" title="">Home</a></li>
<li><a href="" title="">Page 2</a></li>
<li><a href="" title="">Page 3</a></li>
</ul>
</nav>
</header>
<main>
<p><!-- ridiculously long content --></p>
</main>
<footer>
<p>FOOTER CONTENT</p>
</footer>
<script src="navbar.js" type="text/javascript"></script>
</body>
css
nav a {
background: #aaa;
font-size: 1.2rem;
text-decoration: none;
padding: 10px;
}
nav a:hover {
background: #bbb;
}
nav li {
background: #aaa;
padding: 10px 0;
}
nav ul {
background: #aaa;
list-style-type: none;
margin: 0;
padding: 0;
}
@media (min-width: 768px) {
nav ul {
display: flex;
}
}
js
function applyNavbarSticky() {
let header = document.querySelector('body > header:first-child')
let navbar = document.querySelector('nav')
header.style.position = 'sticky'
function setTop() {
let headerHeight = header.clientHeight
let navbarHeight = navbar.clientHeight
let styleTop = navbarHeight - headerHeight
header.style.top = `${styleTop}px`
}
setTop()
window.onresize = function () {
setTop()
}
}
