jQuery实现拉动页面固定顶部显示且自动消失(火狐)

<meta http-equiv="content-type" content="text/html; charset=utf-8"> <title>回到顶部：哭泣的小丑</title> <style> html, body, div, span, applet, object, iframe,h1, h2, h3, h4, h5, h6, p, blockquote, pre,a, abbr, acronym, address, big, cite, code,del, dfn, em, img, ins, kbd, q, s, samp,small, strike, strong, sub, sup, tt, var,b, u, i, center,dl, dt, dd, ol, ul, li,fieldset, form, label, legend, input,table, caption, tbody, tfoot, thead, tr, th, td,article, aside, canvas, details, embed,figure, figcaption, footer, header, hgroup,menu, nav, output, ruby, section, summary,time, mark, audio, video {margin: 0;padding: 0;border: 0;font-size: 100%;} article, aside, details, figcaption, figure,footer, header, hgroup, menu, nav, section {display: block;float:left;}select, input, button,button img, label {vertical-align: middle;}body {font:normal 12px/1.5 "microsoft yahei","微软雅黑",tahoma,arial,helvetica,stheiti; webkit-font-smoothing:antialiased;-moz-font-smoothing: subpixel-antialiased; color:#666;}ol, ul {list-style: none;}blockquote, q {quotes: none;}blockquote:before, blockquote:after,q:before, q:after {content: '';content: none;}table {border-collapse: collapse;border-spacing: 0;}em {font-style: normal}select, input, button, button img, label {vertical-align:middle;}input {font-family:"microsoft yahei","微软雅黑";webkit-font-smoothing:antialiased;-moz-font-smoothing: subpixel-antialiased}input, input:focus, button, button:focus, select,textarea, textarea:focus {outline:none; -moz-outline:none; -webkit-outline:none; }input:focus { outline:none; -moz-outline:none; -webkit-outline:none; }textarea {resize:none;}a {color:#666; text-decoration:none;} a:hover {text-decoration:underline;}a:focus {outline:none; -moz-outline:none;-webkit-outline:none;}body {min-width: 960px;} </style> <style> body{background:#e7e7e7;} .clearfix:before, .clearfix:after, .container_24:before, .container_24:after { content: '.'; display: block; overflow: hidden; visibility: hidden; font-size: 0; line-height: 0; width: 0; height: 0;} .clearfix:after, .container_24:after { clear: both; } .xc_main{width:750px;margin:0 auto;position:relative;} .xc_left{float:left;} .xc_left h1{font-size:24px;padding-top:25px;} .xc_right{float:right;width:600px;} .xc_right .xc_list{margin:10px 0 10px 0;} .xc_list_top,.xc_list_main{background:#fff;padding:10px;border:1px solid #ccc;} .xc_list_top{margin-bottom:10px;} .xc_gg{width:90px;height:90px;border:1px solid #ccc;background:#fff;text-align:center;} .xc_bottom{height:650px;background:#fff;padding:10px;border:1px solid #ccc;position:relative;} </style> <div class="xc_main clearfix"> <div class="clearfix" style="margin-top:90px;float:left;"> <div class="xc_left"> <div class="xc_gg"> <h1>小丑</h1> <div style="margin-top:40px;">q群:<em style="color:#0069d6;">150508281</em> </div> </div> </div> </div> <div class="xc_right clearfix"> <div class="xc_list"> <div class="xc_list_top" id="xc_list_top">top 1</div> </div> <div class="xc_list"> <div class="xc_list_top">top 2</div> </div> <div class="xc_list"> <div class="xc_list_top">top 3</div> </div> <div class="xc_list"> <div class="xc_list_top">top 4</div> </div> <div class="xc_list"> <div class="xc_list_top">top 5</div> </div> <div class="xc_list"> <div class="xc_list_top">top 6</div> </div> </div> </div> <div class="xc_bottom clearfix" id="footerdestinationbox"> <div style="position:absolute;top:40px;right:50px;"> by @哭泣的小丑</div> </div>
[ctrl+a 全选 注:引入外部js需再刷新一下页面才能执行]