Explanation of proprietary conditional comments in IE browser under HTML_Experience exchange

In the process of learning and applying WEB standard web pages, the compatibility of web pages with browsers is an issue that is often encountered. Among them, Microsoft's Internet Explorer (IE for short) occupies most of the browser market, in addition to Firefox, Opera, etc. Compatibility with these browsers is required.
At the same time, as far as IE is concerned, due to the upgrade and replacement of IE versions, the current browsers mainly use IE5 (IE5.5), IE6 and IE7. These three versions have different interpretation and execution of the WEB standard web pages (XHTML CSS) we produced. Moreover, other non-IE browsers interpret certain CSS differently from IE. Therefore, relevant attributes can be defined in a targeted manner through proprietary conditional comments in IE browser.
Original address: http://www.quirksmode.org/css/condcom.html
Conditional comments can only be used in Explorer 5 Windows (hereinafter referred to as IE) (conditional comments are supported starting from IE5). If you have multiple IEs installed, conditional comments will be based on the highest version of IE (currently IE 7).
Conditional comments can only be used under windows Internet Explorer (hereinafter referred to as IE), so we can add special instructions for IE through conditional comments.
To put it simply, conditional comments are some if judgments, but these judgments are not executed in the script, but directly in the html code, such as:



1. The basic structure of conditional comments is the same as HTML comments (). Therefore browsers other than IE will treat them as ordinary comments and ignore them completely.
2. IE will use the if condition to determine whether to parse the content in the conditional comment like parsing ordinary page content.
3. Conditional comments use the HTML comment structure, so they can only be used in HTML files, not CSS files.
You can use the following code to detect the current IE browser version (note: the effect will not be visible in non-IE browsers)


 

Version 5.0

 
 
 

What should you do if the current browser is IE, but the version is lower than IE5? You can use






This distinguishes the execution of CSS by IE7 and IE6 downward browsers to achieve compatibility. At the same time, the default css.css in the first line is also compatible with other non-IE browsers.
Note: The default CSS style should be located on the first line of the HTML document, and all content for conditional comment judgment must be located after the default style.
For example, if the following code is executed in IE browser, it will be displayed in red, but in non-IE browser, it will be displayed in black. If the conditional comment judgment is placed on the first line, it cannot be implemented. This example question is very useful in explaining how to solve the compatibility issues between IE browsers and non-IE browsers on web pages.