syntax
child:
>
<nav> <ul> <li></li> </ul> </nav>
Sibling:
+ (Peer label)
<div></div> <p></p> <blockquote></blockquote>
Combination symbol:
()
<div> <p><span></span></p> </div> <blockquote></blockquote>
Number of indications:
*
<ul> <li></li> <li></li> <li></li> <li></li> <li></li> </ul>
Create element, ID, class
<head> </head>
<div id="head"></div>
<div class="head"></div>
Html content
!
<! DOCTYPE html> <html lang="en"> <head> <meta charset="UTF-8"> <title>Document</title> </head> <body> </body> </html>