
<!DOCTYPE html>
<html lang="en">
<head>
    <link rel="shortcut icon" href="#" />
    <meta charset='UTF-8'>
    <meta name="viewport" content="width=device-width, initial-scale=1.0">
    <meta http-equiv="X-UA-Compatible" content="ie=edge" >
    <title>sdk demo ls </title>
    <style>
        #rel{
            position: relative;
        }
        #rel button{
            position: absolute;
        }
        *{
            margin: 5px 5px;
        }
        button{
            width: 70px;
            he