#arume-background{ filter: grayscale(100%);
-webkit-filter:grayscale(100%);
-moz-filter: grayscale(100%);
-ms-filter: grayscale(100%);
-o-filter: grayscale(100%);
position: fixed; width:calc(100% - 400px); margin:50px; opacity:0.12;z-index:-1;
 }

@media only screen and (max-width:768px) {
#arume-background{ width:calc(100% - 100px); }
}