phper应该懂得的css中高级知识

1.对WEB标准以及W3C的理解与认识
l  标签闭合、标签小写、不乱嵌套、提高搜索机器人搜索几率;
l  使用外链css和js脚本、结构行为表现的分离、文件下载与页面速度更快;
l  内容能被更多的用户所访问、内容能被更广泛的设备所访问、更少的代码和组件;
l  容易维护、改版方便,不需要变动页面内容;
l  提供打印版本而不需要复制内容、提高网站易用性;
2.xhtml和html有什么区别
HTML是一种基本的WEB网页设计语言,XHTML是一个基于XML的置标语言
最主要的不同:
l  XHTML 元素必须被正确地嵌套。
l  XHTML 元素必须被关闭。
l  标签名必须用小写字母。
l  XHTML 文档必须拥有根元素。
3.Doctype? 严格模式与混杂模式-如何触发这两种模式,区分它们有何意义?
用于声明文档使用那种规范(html/Xhtml)一般为 严格 过度 基于框架的html文档
加入XMl声明可触发,解析方式更改为IE5.5拥有IE5.5的bug
4.行内元素有哪些?块级元素有哪些?CSS的盒模型?
块级元素:div p h1 h2 h3 h4 form ul
行内元素: a b br i span input select
Css盒模型:内容,border,margin,padding
5.CSS引入的方式有哪些? link和@import的区别是?
内联 内嵌 外链 导入
区别 :同时加载;前者无兼容性,后者CSS2.1以下浏览器不支持;Link支持使用javascript改变样式,后者不可
6.CSS选择符有哪些?哪些属性可以继承?优先级算法如何计算?内联和important哪个优先级高?
l  标签选择符 类选择符 id选择符
l  继承不如指定Id>class>标签选择l  内联和important优先级高是后者优先级高
7.前端页面有哪三层构成,分别是什么?作用是什么?
结构层 Html 表示层 CSS 行为层 js
8.css的基本语句构成是?
选择器{属性1:值1;属性2:值2;……}
9.你做的页面在哪些流览器测试过?这些浏览器的内核分别是什么?
Ie(Ie内核) 火狐(Gecko) 谷歌(webkit)opear(Presto)
10.写出几种IE6 BUG的解决方法
n  双边距BUG float引起的 使用display
n  像素问题 使用float引起的 使用dislpay:inline -3px
n  超链接hover 点击后失效 使用正确的书写顺序 linkvisited hover activen  Ie z-index问题 给父级添加position:relative
n  Png 透明 使用js代码改
n  Min-height 最小高度 !Important 解决’
n  select 在ie6下遮盖 使用iframe嵌套
n  为什么没有办法定义1px左右的宽度容器(IE6默认的行高造成的,使用over:hidden,zoom:0.08line-height:1px)
11.<img>标签上title与alt属性的区别是什么?
l  Alt 当图片不显示是用文字代表。l  Title 为该属性提供信息
12.描述css reset的作用和用途。
Reset重置浏览器的css默认属性浏览器的品种不同,样式不同,然后重置,让他们统一
13.解释css sprites,如何使用。
Css 精灵 把一堆小的图片整合到一张大的图片上,减轻服务器对图片的请求数量
14.浏览器标准模式和怪异模式之间的区别是什么?
l  盒子模型 渲染模式的不同
l  使用window.top.document.compatMode 可显示为什么模式
15.你如何对网站的文件和资源进行优化?期待的解决方案包括:
l  文件合并
l  文件最小化/文件压缩
l  使用CDN托管
l  缓存的使用
16.什么是语义化的HTML?
直观的认识标签 对于搜索引擎的抓取有好处
17.清除浮动的几种方式,各自的优缺点
  使用空标签清除浮动clear:both(理论上能清楚任何标签,,,增加无意义的标签)
  使用overflow:auto(空标签元素清除浮动而不得不增加无意代码的弊端,使用zoom:1用于兼容IE)
  是用afert伪元素清除浮动(用于非IE浏览器)

Advertisements

How To Create an IE-Only Stylesheet

If you read this blog, there is a 99% chance you’ve had a hair-pulling experience with IE. But if you are worth your salt as a CSS coder, you should be able to deal with it. I am of the opinion that you can handle anything IE can throw at you without the use of hacks. Hacks are dangerous, since they are based on non-standard exploits, you can’t predict how they are going to behave in future browsers. The tool of choice for fighting IE problems is the conditional stylesheet. IE provides comment tags, supported all the way up to the current IE 8 to target specific versions, as well as greater-than/less-than stuff for targeting multiple versions at once.

Why use conditional stylesheets?
  • You got problems, they need fixin’
  • Keeps your code hack-free and valid
  • Keeps your main stylesheet clean
  • Perfectly acceptable technique, sanctioned by Microsoft

And remember, these conditional tags don’t have to be used only for CSS. You could load JavaScript, or even use them down in the content of your site to display special IE-specific messages.

The Code

This would go in your <head> with all the other regular CSS <link>ed CSS files. The opening and closing tags should be familiar, that’s just regular ol’ HTML comments. Then between the brackets, “IF” and “IE” should be fairly obvious. The syntax to note is “!” stand for “not”, so !IE means “not IE”. gt means “greater than”, gte means “greater than or equal”, lt means “less than”, lte means “less than or equal.”

Target ALL VERSIONS of IE
<!--[if IE]>
	<link rel="stylesheet" type="text/css" href="all-ie-only.css" />
<![endif]-->
Target everything EXCEPT IE
<!--[if !IE]><!-->
	<link rel="stylesheet" type="text/css" href="not-ie.css" />
 <!--<![endif]-->
Target IE 7 ONLY
<!--[if IE 7]>
	<link rel="stylesheet" type="text/css" href="ie7.css">
<![endif]-->
Target IE 6 ONLY
<!--[if IE 6]>
	<link rel="stylesheet" type="text/css" href="ie6.css" />
<![endif]-->
Target IE 5 ONLY
<!--[if IE 5]>
	<link rel="stylesheet" type="text/css" href="ie5.css" />
<![endif]-->
Target IE 5.5 ONLY
<!--[if IE 5.5000]>
<link rel="stylesheet" type="text/css" href="ie55.css" />
<![endif]-->
Target IE 6 and LOWER
<!--[if lt IE 7]>
	<link rel="stylesheet" type="text/css" href="ie6-and-down.css" />
<![endif]-->
<!--[if lte IE 6]>
	<link rel="stylesheet" type="text/css" href="ie6-and-down.css" />
<![endif]-->
Target IE 7 and LOWER
<!--[if lt IE 8]>
	<link rel="stylesheet" type="text/css" href="ie7-and-down.css" />
<![endif]-->
<!--[if lte IE 7]>
	<link rel="stylesheet" type="text/css" href="ie7-and-down.css" />
<![endif]-->
Target IE 8 and LOWER
<!--[if lt IE 9]>
	<link rel="stylesheet" type="text/css" href="ie8-and-down.css" />
<![endif]-->
<!--[if lte IE 8]>
	<link rel="stylesheet" type="text/css" href="ie8-and-down.css" />
<![endif]-->
Target IE 6 and HIGHER
<!--[if gt IE 5.5]>
	<link rel="stylesheet" type="text/css" href="ie6-and-up.css" />
<![endif]-->
<!--[if gte IE 6]>
	<link rel="stylesheet" type="text/css" href="ie6-and-up.css" />
<![endif]-->
Target IE 7 and HIGHER
<!--[if gt IE 6]>
	<link rel="stylesheet" type="text/css" href="ie7-and-up.css" />
<![endif]-->
<!--[if gte IE 7]>
	<link rel="stylesheet" type="text/css" href="ie7-and-up.css" />
<![endif]-->
Target IE 8 and HIGHER
<!--[if gt IE 7]>
	<link rel="stylesheet" type="text/css" href="ie8-and-up.css" />
<![endif]-->
<!--[if gte IE 8]>
	<link rel="stylesheet" type="text/css" href="ie8-and-up.css" />
<![endif]-->
Universal IE 6 CSS

Dealing with IE 6 and below is always an extra-special challenge. These days people are dropping support for it right and left, including major businesses, major web apps, and even governments. There is a better solution than just letting the site go to hell, and that is to server IE 6 and below a special stripped-down stylesheet, and then serve IE 7 and above (and all other browsers) the regular CSS. This is been coined the universal IE 6 CSS.

<!--[if !IE 6]><!-->
  <link rel="stylesheet" type="text/css" media="screen, projection" href="REGULAR-STYLESHEET.css" />
<!--<![endif]-->

<!--[if gte IE 7]>
  <link rel="stylesheet" type="text/css" media="screen, projection" href="REGULAR-STYLESHEET.css" />
<![endif]-->

<!--[if lte IE 6]>
  <link rel="stylesheet" type="text/css" media="screen, projection" href="http://universal-ie6-css.googlecode.com/files/ie6.0.3.css" />
<![endif]-->
Hacks

If you must…

IE-6 ONLY
* html #div {
    height: 300px;
}
IE-7 ONLY
*+html #div {
    height: 300px;
}
IE-8 ONLY
#div {
  height: 300px/;
}
IE-7 & IE-8
#div {
  height: 300px\9;
}
NON IE-7 ONLY:
#div {
   _height: 300px;
}
Hide from IE 6 and LOWER:
#div {
   height/**/: 300px;
}
html > body #div {
      height: 300px;
}
Argument against conditional stylesheets

We shouldn’t need them. They are against the spirit of web standards.

Argument for conditional stylesheets

Yeah, but we do need them.

Additional Resources