html,body{
margin:0;
padding:0;
}

body { 

background-color: #efefef;
     background-image:url(https://img2018.cnblogs.com/blog/1926570/202001/1926570-20200125203454948-1179990388.jpg); 
     background-repeat: no-repeat; 
     background-attachment: fixed; 
     background-position: center 0; 
     background-size: cover; 
    padding-top:0px;

min-width:750px;
  }
#wrapper{
margin:0 auto;
width:750px;


}