繁體中文当前位置: 首页 > 图文教程 > 网页制作 > CSS样式表 > 英文教程:用CSS控制和操作BODY标记
- CSS样式表
- CSS优先级规则的细节
- CSS失效，原来是和网页第一段代码有关
- 你真的了解CSS吗？你是属于哪个层次？
- 让样式表CSS代码更加专业规范
- 建议网页设计师用CSS制作网站导航菜单
- 简单学习css组合与CSS嵌套的写法
- CSS学习之css代码的简写的十条规则
- 条件CSS的介绍
- CSS教程:网页中多个样式表顺序问题
- CSS教程：网页版面设计无效的10个原因
- 页面重构工程师应该具有的技能和素质
- 选择正确DOCTYPE解决CSS在网页失效问题
- Opera中国的WEB标准课程
- 简单介绍Web Developer插件制作网页
- CSS布局带来的巨大影响:CSS display属性值
- 用div css模拟表格对角线
- IE Firefox在css中的差别 (部分)
- 不用js可以实现信息提示效果
- CSS解决未知高度的垂直水平居中自适应问题
- CSS cursor 属性 -- 鼠标指针样式效果
CSS样式表 中的 英文教程:用CSS控制和操作BODY标记
出处:互联网 整理: 软晨网（RuanChen.com） 发布: 2009-09-28 浏览: 102 ::
收藏到网摘: n/a
Let’s say you want to change the color of your links on just your contact page to red. They are blue on every other page, but it just makes sense for them to be red on your contact page (for some reason). There are a couple ways you could go about this.
- You could declare a separate stylesheet for your contact page. This isn’t ideal, because it’s redundant. If you make any other changes, you’ll always have to make them both on the main stylesheet and the contact page stylesheet.
- You could give all those links a unique class on that page. This isn’t ideal, because it isn’t very semantic and it’s also redundant. Why apply a class to every single link on the page when they really aren’t any different from links elsewhere on the site, contextually speaking?
- The best solution is to give your the body a unique ID. This solves the problem perfectly. You can use the same stylesheet and target just the links you want to with a single CSS selector.
How it’s done
Simple, literally just apply the ID to the body tag:
...
</head>
<body id="contact-page"> ...Now for our example of making all links on the contact page red instead of blue, just use some CSS like this:
a {
color: blue;
}
#contact-page a { color: red;
}
How about a more practical example?
You got it. One of the most useful implementations of this technique is within navigation. Take a look at this sample navigation:
See how the forums tab is the “active” tab? Certainly that’s just a slight change in CSS, probably just a shift in the position of a background image. Perhaps the XHTML looks something like this:
...
<li><a href="/fieldtips">Field tips</a></li>
<li class="active"><a href="/forums">Forums</a></li>
...The “active” class applied to the list item is what shifts the background image. That’ll do the trick, but what about when we move to the Field Tips page? We will have to remove the active class from the forums tab and apply it to the the Field Tips tab. That’s not very convenient. That means the code for the navigation block is unique on every single page of the site. So let’s say down the road we want to add a Contact tab, we’ll have to alter the code on every single page. No fun.
Let’s do this a little smarter. First we don’t want to include the navigation block of code on every page, we want to include it, probably with a simple PHP include like this:
<?php include_once("nav.html"); ?>
But then how do we apply the “active” class to the current navigation list element?
This is where apply what we just learned about giving unique ID’s to the body! Instead of applying a class to only the active list element, let’s apply a unique class to each separate list item as well as give our body an unique ID.
...
</head>
<body id="field-tips"> ... <li class="fieldtips"><a href="/fieldtips">Field tips</a></li> <li class="forums"><a href="/forums">Forums</a></li> ...Now we can target specific elements in the navigation with some clever CSS:
#field-tips li.fieldtips, #forums li.forums { background-position: bottom;
}This means that the code for the navigation block can stay the same on every page, yet only the navigation element native to that page will be affected by this CSS and “flip” to the active state.
Let’s get even more dynamic
Reader Brian left an awesome comment on how you can use PHP to apply the unique ID to to the body element:
<body id="<?= basename(Let’s say you want to change the color of your links on just your contact page to red. They are blue on every other page, but it just makes sense for them to be red on your contact page (for some reason). There are a couple ways you could go about this.
- You could declare a separate stylesheet for your contact page. This isn’t ideal, because it’s redundant. If you make any other changes, you’ll always have to make them both on the main stylesheet and the contact page stylesheet.
- You could give all those links a unique class on that page. This isn’t ideal, because it isn’t very semantic and it’s also redundant. Why apply a class to every single link on the page when they really aren’t any different from links elsewhere on the site, contextually speaking?
- The best solution is to give your the body a unique ID. This solves the problem perfectly. You can use the same stylesheet and target just the links you want to with a single CSS selector.
How it’s done
Simple, literally just apply the ID to the body tag:
...
</head>
<body id="contact-page"> ...
Now for our example of making all links on the contact page red instead of blue, just use some CSS like this:
a {
color: blue;
}
#contact-page a { color: red;
}
How about a more practical example?
You got it. One of the most useful implementations of this technique is within navigation. Take a look at this sample navigation:
See how the forums tab is the “active” tab? Certainly that’s just a slight change in CSS, probably just a shift in the position of a background image. Perhaps the XHTML looks something like this:
...
<li><a href="/fieldtips">Field tips</a></li>
<li class="active"><a href="/forums">Forums</a></li>
...
The “active” class applied to the list item is what shifts the background image. That’ll do the trick, but what about when we move to the Field Tips page? We will have to remove the active class from the forums tab and apply it to the the Field Tips tab. That’s not very convenient. That means the code for the navigation block is unique on every single page of the site. So let’s say down the road we want to add a Contact tab, we’ll have to alter the code on every single page. No fun.
Let’s do this a little smarter. First we don’t want to include the navigation block of code on every page, we want to include it, probably with a simple PHP include like this:
<?php include_once("nav.html"); ?>
But then how do we apply the “active” class to the current navigation list element?
This is where apply what we just learned about giving unique ID’s to the body! Instead of applying a class to only the active list element, let’s apply a unique class to each separate list item as well as give our body an unique ID.
...
</head>
<body id="field-tips"> ... <li class="fieldtips"><a href="/fieldtips">Field tips</a></li> <li class="forums"><a href="/forums">Forums</a></li> ...
Now we can target specific elements in the navigation with some clever CSS:
#field-tips li.fieldtips, #forums li.forums { background-position: bottom;
}
This means that the code for the navigation block can stay the same on every page, yet only the navigation element native to that page will be affected by this CSS and “flip” to the active state.
Let’s get even more dynamic
Reader Brian left an awesome comment on how you can use PHP to apply the unique ID to to the body element:
___FCKpd___6
This will return the name of the PHP file being executed as the ID (e.g. body id=”index.php”). To leave off the .php part, just remove the “.php” part.
SERVER['PHP_SELF'], ".php")?>">This will return the name of the PHP file being executed as the ID (e.g. body id=”index.php”). To leave off the .php part, just remove the “.php” part.
评论 (0) All
