js+css实现回到顶部按钮（backtotop）_javascript技巧

p#back-to-top{
 position:fixed;
 bottom:100px;
 right:80px;
}
p#back-to-top a{
 text-align:center;
 text-decoration:none;
 color:#d1d1d1;
 display:block;
 width:30px;
 /*使用CSS3中的transition属性给跳转链接中的文字添加渐变效果*/
 -moz-transition:color1s;
 -webkit-transition:color1s;
 -o-transition:color1s;
}
p#back-to-top a:hover{
 color:#979797;
}
p#back-to-top a span{
 background:#d1d1d1 url(../images/arrow_up.png) no-repeat center center;
 border-radius:6px;
 display:block;
 height:30px;
 width:30px;
 margin-bottom:5px;
 /*使用CSS3中的transition属性给标签背景颜色添加渐变效果*/
 -moz-transition:background1s;
 -webkit-transition:background1s;
 -o-transition:background1s;
}
#back-to-top a:hover span{
 background:#979797 url(../images/arrow_up.png) no-repeat center center;
}