CSS import or multiple CSS files
I originally wanted to include a .css in my HTML doc that loads multiple other .css files in order to divide up some chunks of code for development purposes.
I have created a test page:
<!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Transitional//EN" "http://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd">
<html xmlns="http://www.w3.org/1999/xhtml">
<head>
<title>The Recipe Site</title>
<link rel='stylesheet' href='/css/main.css'>
<link rel='stylesheet' href='/css/site_header.css'>
<!-- Let google host jQuery for us, maybeb replace with their api -->
<script type="text/javascript" src="http://ajax.googleapis.com/ajax/libs/jquery/1.4.1/jquery.min.js"></script>
<script type="text/javascript" src="/js/main.js"></script>
</head>
<body>
<div id="site_container">
<div id="site_header"><?php include_once($r->base_dir . "inc/site_header.inc.php"); ?><!-- Include File, Update on ajax request. --></div>
<div id="site_content">
Some main content.
</div>
<div id="site_footer"><?php include_once($r->base_dir . "inc/site_footer.inc.php"); ?><!-- Include File, Update on ajax request. --></div>
</div>
</body>
</html>
File: /css/main.css
/* Reset Default Padding & Margin */
* {
margin: 0;
padding: 0;
border: 0;
}
/* Set Our Float Classes */
.clear { clear: both; }
.right { float: right; }
.left { float: left; }
/* Setup the main body/site container */
body {
background: url(/images/wallpaper.png) repeat;
color: #000000;
text-align: center;
font: 62.5%/1.5 "Lucida Grande", "Lucida Sans", Tahoma, Verdana, sans-serif;
}
#site_container {
background-color: #FFFFFF;
height: 100%;
margin-left: auto;
margin-right: auto;
text-align: left;
width: 100%;
}
/* Some style sheet includes */
/* @import "/css/site_header.css"; */
/* Default Font Sizes */
h1 { font-size: 2.2em; }
h2 { font-size: 2.0em; }
h3 { font-size: 1.8em; }
h4 { font-size: 1.6em; }
h5 { font-size: 1.4em; }
p { font-size: 1.2em; }
/* Default Form Layout */
input.text {
padding: 3px;
border: 1px solid #999999;
}
/* Default Table Reset */
table {
border-spacing: 0;
border-collapse: collapse;
}
td{
text-align: left;
font-weight: normal;
}
/* Cause not all browsers know what HTML5 is... */
header { display:block;}
footer { display:block;}
and now the file: /css/site_header.css:
#site_header {
background-color: #c0c0c0;
height: 100px;
position: absolute;
top: 100px;
width: 100%;
}
Problem:
When I use the above code, the site_header div does not have any formatting/background. When I remove the link line from the HTML doc开发者_StackOverflow中文版 for site_header.css and instead use an @import url("/css/site_header.css"); in my main.css file, the same results -- nothing gets rendered for for the same div.
Now when I take the CSS markup from site_header.css and add it to main.css, the div gets rendered fine...
So I am wondering if having multiple css files is somehow not working... or maybe having that css markup at the end of my previous css is somehow conflicting, though I cannot find a reason why it would.
The @import directive has to come first in your CSS. As soon as one style is hit by the browser, all other import lines will be ignored.
To quote WC3:
"any @import rules must precede all other rules (except the @charset rule, if present)"
See http://www.w3.org/TR/CSS2/cascade.html#at-import
One thing to consider, is that each @import still causes an HTTP request, so it's not any more efficient than using multiple link tags. In fact it may be less efficient as imports may be sequential rather than parallel requests. See this article. IMO it also adds complexity because you end up managing CSS references in two places (head tag of markup plus 1 or more CSS files) vs a simple list of link tags.
I'd also recommend where you can combining CSS files when your site is in production as it will reduce HTTP overhead.
Can I just say, pet peeve here, but place images related to the CSS file in the CSS folder itself, not in /images/.
The point of CSS is the separation of style and content, and only content images should go in /images/. Any images called by the CSS should be placed in the same directory and called pathlessly, e.g.:
body {
background: url(wallpaper.png) repeat;
}
That way at a later date if it comes to changing the style, or making multiple styles it's just a case of updating one link and moving one folder (/css/) rather than having a mess of images scattered all over the filesystem. Plus it's always a bad idea to use absolute paths to files (such as /images/wallpaper.png).
First of all, you have invalid markup. The link tag must be closed...
<link rel="stylesheet" href="/css/main.css" />
Second, why don't you use double-quotes consistently for element attributes (here in the link tag you happen to use single-quote)? This is not part of the problem, but I find it daunting that you would intermingle various syntax conventions like this.
Lastly, I would not recommend using @import because it does not offer a compelling benefit. It must be the first thing in the CSS file. An additional HTTP request still has to be made for each of the additional CSS file(s). And on top of that, IE cokes when you to specify a target media for imports. I stick to the good old classic link tag because it just works (given that you have valid markup!).
Use firebug to inspect the div and see what styles are being applied to it, you might get some more insight.
use @import rule into your main.css file like:
@import url("css/site_header.css");(this code should be on top of your main.css)
the above import snippet will bind your multiple css files into single css
then that main.css file use into your HTML.
For any issues with CSS like this I would recommend using firebug. You will be able to see if your site_header.css is loading properly.
If it is loading you will be able to see which styles are being applied to which elements, perhaps some are being overwritten?
加载中,请稍侯......
精彩评论