.pc {
      display: block;
      margin:auto;
}
.sp {
      display: none;
      margin:auto;
}

@media screen and (max-width: 640px){
    .pc {
      display: none;
	}
    .sp {
      display: block;
	}
    #header{
	  overflow:hidden;
	}
    #header_btn img{
      left: 447px;
      position: absolute;
      top: 11px;
    }
#header_logo{
   position: absolute; 
   top: 18px; 
   left: 10px;
}
}