All labels must be lowercase
In XHTML, all tags must be lowercase, and the tongue must not be interspersed with uppercase and uppercase, nor can all be uppercase. Things are as follows.
Error: <Head></Head><Body></Body>
Correct: <head></head><body></body>
Tags must be paired
For example, <p>...</p>, <a>...</a>, <div>...</div> tags, etc., when a tag appears, there must be a corresponding end tag, which is indispensable, just like brackets in any programming language.
Error: Hello everyone<p>It's really good
Correct: <p>Hello everyone</p><p>It's really good</p>
Summarize:
The label order must be correct, from the outside to the inside, and the labels are covered layer by layer, so suppose you write div first and then h1, and at the end you need to write h1 first and then div. Just remember a principle that comes in and out first, and the tag that pops up first should end.
error: <div><h1>hello</div></h1>
Correct: <div><h1>csdn</h1></div>
All properties must be double quoted
It is stipulated that even single quotes cannot be used in XHTML 1.0, so double quotes must be used throughout the process.
error: <div style=font-size:11px>csdn</div>
Correct: <div style=font-size:11px>csdn</div
Target=_blank is not allowed
Starting from XHTML1.1, target attribute is completely disabled. If you want to have the function of opening a new window, you must rel=external and use it to achieve this effect with JavaScript.
error: <a href=http://blog.mukispace.com target=_blank>csdn</a>
Correct: <a href=http://blog.mukispace.com rel=external>csdn</a> stick out his tongue