<frameset>标签对,它被用来组织多个窗口(框架)
<!DOCTYPE html>
<html>
<head>
<title></title>
</head>
<frameset cols="25%,50%,25%">
<frame style="background-color: yellow ">
<frame style="background-color: green ">
<frame style="background-color: lightbl ">
</frameset>
</html>