php我是php、html和css的初学者例如，我想将徽标更改为居中，但它没有更改我使用xampp来运行我的php文件我不确定我是否使用了正确的链接方式css到php文件
<?php include('server.php'); ?>
<!DOCTYPE html>
<html lang="en" xmlns="http://www.w3.org/1999/xhtml">
<head>
<title>Home page</title>
<meta charset="UTF-8">
<meta name="viewport" content="width=device-width, initial-scale=1.0">
<meta http-equiv="X-UA-Compatible" content="ie=edge">
<link rel="stylesheet" href="https://maxcdn.bootstrapcdn.com/font-awesome/4.7.0/css/font-awesome.min.css">
<script src="http://code.jquery.com/jquery-3.3.1.js"></script>
<link href="https://fonts.googleapis.com/css?family=Poppins:200,300,400,500,600" rel="stylesheet">
<link rel="stylesheet" href="StyleIndex.css">
</head>
<body>
<header class="Logo">
<a href="index.php">
<img alt="logo" src="logo3.jpg" />
</a>
</header>
<nav>
<div>
<i class="fa fa-bars"></i>
</div>
<ul>
<li><a href="index.html">Home</a></li>
<li><a href="#">Drop 1 <i class="fa fa-sort-desc"></i></a>
<ul>
<li><a href="#">m 1</a></li>
<li><a href="#">m 2</a></li>
<li><a href="#">m 3</a></li>
<li><a href="#">m 4</a></li>
</ul>
</li>
<li><a href="#">Drop 2 <i class="fa fa-sort-desc"></i></a>
<ul>
<li><a href="#">m 1</a></li>
<li><a href="#">m 2</a></li>
<li><a href="#">m 3</a></li>
<li><a href="#">m 4</a></li>
</ul>
</li>
<li><a href="About.php">About</a></li>
<li><a href="login.php">Logout</a></li>
</ul>
</nav>
<script type="text/javascript">
$("nav div").click(function() {
$("ul").slideToggle();
$("ul ul").css("display", "none");
});
$("ul li").click(function() {
$("ul ul").slideUp();
$(this).find('ul').slideToggle();
});
$(window).resize(function() {
if($(window).width() > 768) {
$("ul").removeAttr('style');
}
});
</script>
<div class="semiProfile">
<div class="avatar">
<img src="avatar.png" />
</div>
<div class="Username">
<?php if (isset($_SESSION['username'])) : ?>
<p class="username"><strong><?php echo $_SESSION['username']; ?></strong></p>
<?php endif ?>
</div>
</div>
<div class="Content">
<div class="news">
<p class="status">
</p>
</div>
<div class="Chat">
<Form class="chatBox">
<input class="statusBar" type="text" placeholder="Write your status ...!" />
<button>Send</button>
</Form>
</div>
</div>
<div class="NewQuestion">
<div class="avatar1">
<img src="avatar.png" />
</div>
<div class="Username">
<?php if (isset($_SESSION['username'])) : ?>
<p class="username1"><strong><?php echo $_SESSION['username']; ?></strong></p>
<?php endif ?>
</div>
<div class="Question">
<p class="question">
This is the area where the new and trending questions are written on the website
</p>
</div>
</div>
<footer class="footer">
Copyrights!
</footer>
</body>
</html>
我试着设计它的风格，但对它没有影响这是我的css文件StyleIndex.css
* {
margin: 0px;
padding: 0px;
}
body {
margin: 0;
padding: 0;
background-color:#161515;
}
.logo img{
position: absolute;
left: 100px;
}
.nav{
position: absolute;
}
.nav .a
{
padding: 20px;
}
ul {
margin: 0;
padding: 0;
list-style-type: none;
background-color: rgb(34, 33, 33);
position: relative;
}
ul li {
display: inline-block;
}
ul li a {
color: aliceblue;
text-decoration: none;
padding: 15px;
display: block;
}
ul li:hover {
background: lightgrey;
}
ul ul {
position: absolute;
min-width: 200px;
background: lightgrey;
display: none;
}
ul ul li {
display: block;
background: #e3e3e3;
}
ul li:hover ul {
display: block;
}
ul li i {
color: aliceblue;
float: right;
padding-left: 20px;
}
nav div {
background-color: rgb(34, 33, 33);
color: #292929;
font-size: 24px;
padding: 0.6em;
cursor: pointer;
display: none;
}
@media(max-width: 768px) {
nav div {
display: block;
}
ul {
display: none;
position: static;
background-color: rgb(34, 33, 33);
}
ul li {
display: block;
}
ul ul {
position: static;
background-color: rgb(34, 33, 33);
}
}
.semiProfile
{
width: 300px;
height: 100px;
padding: 50px;
border: 1px solid black;
background-color: rgb(34, 33, 33);
position:absolute;
}
.avatar img
{
max-width: 80px;
max-height: 80px;
}
.logout
{
margin: 15px 0 0;
color:aliceblue;
font-size: 12px;
}
.username
{
position: absolute;
left: 150px;
top: 60px;
color:aliceblue;
}
.About
{
margin: 15px 0 0;
color: aliceblue;
font-size: 12px;
}
.Logo img
{
max-width: 80px;
max-height: 80px;
}
.footer
{
position: absolute;
left: 200px;
top: 900px;
color: aliceblue;
}
.Contect
{
width: 360px;
padding: 10% 0 0;
margin: auto;
}
.news
{
position: relative;
z-index: 1;
background: rgb(34, 33, 33);
max-width: 360px;
margin: 0 auto 20px;
padding: 20px;
text-align: center;
border: 1px solid black;
}
.status
{
margin: 15px 0 0;
color: aliceblue;
font-size: 15px;
}
.Chat
{
position: relative;
z-index: 1;
background: rgb(34, 33, 33);
max-width: 360px;
margin: 0 auto 20px;
padding: 20px;
text-align: center;
border: 1px solid black;
}
.Chat input
{
font-family: "Roboto", sans-serif;
outline: solid;
background: #f2f2f2;
width: 100%;
border: 0;
margin: 0 0 15px;
padding: 15px;
box-sizing:border-box;
font-size: 14px;
}
.Chat button
{
font-family: "Roboto", sans-serif;
text-transform: uppercase;
outline: 0;
background: #000000;
width: 100%;
border: 0;
padding: 15px;
color: #FFFFFF;
font-size: 14px;
cursor: pointer;
}
.Chat button:hover, .Chat button:active
{
background: #630645;
}
.username1
{
position: absolute;
top: 10px;
left: 110px;
color: aliceblue;
}
.avatar1 img
{
max-width: 80px;
max-height: 80px;
border-radius: 50%;
top: 10px;
left: 20px;
position:absolute;
}
.NewQuestion
{
width: 300px;
height: 100px;
padding: 50px;
border: 1px solid black;
background-color: rgb(34, 33, 33);
position: absolute;
right: 90px;
top: 135px;
}
.question
{
position: absolute;
top: 50px;
left: 110px;
color: aliceblue;
}
我发现了问题，问题来自examplep我不确定发生了什么，但我用过其他程序，现在它起作用了在检查了网络选项卡后，我看到css文件在一段时间后出现它有一个旧版本，我不知道为什么，但我使用了PhpStorm，然后我制作了localhost使用PhpStorm，现在它起作用了，感谢人们试图帮助我：(