#skipping {  
  position: absolute;
  margin-left: -999px;
  width: 990px;
  float: left;
}

#notskipping {
  position: static;
  margin-left: auto;
  width: auto;
  float: left;
}  


#maintop {
  width: 750px;
}

@media screen and (max-width: 600px){  

#notskipping {  
  position: absolute;
  margin-left: -999px;
  width: 990px;
  float: left;
}

#skipping {
  position: static;
  margin-left: auto;
  width: auto;
  float: left;
} 

#maintop {
  width: auto;
}
 
}