CSS背景设置

html{
    height:100%;
}

body{
    background-image: url(img.gif);
    background-repeat: no-repeat;
    background-position: top;

    background-position: right;

    background-position: bottom;  html要设置成100% 才有效果

    background-position: center;

    background-position: right top;

    等比例绽放
    background-size: cover;  

    background-size: 100%;

    background-size:contain;  
    固定背景图片
    background-attachment: fixed;
    background-attachment: scroll;

   
}