How can I apply this for firefox and all browsers.

/* For the "inset" look only */
html {
    overflow: auto;
}
body {
    position: absolute;
    top: 20px;
    left: 20px;
    bottom: 20px;
    right: 20px;
    padding: 30px; 
    overflow-y: scroll;
    overflow-x: hidden;
}

/* Let's get this party started */
::-webkit-scrollbar {
    width: 12px;
}
 
/* Track */
::-webkit-scrollbar-track {
    -webkit-box-shadow: inset 0 0 6px rgba(0,0,0,0.3); 
    -webkit-border-radius: 10px;
    border-radius: 10px;
}
 
/* Handle */
::-webkit-scrollbar-thumb {
    -webkit-border-radius: 10px;
    border-radius: 10px;
    background: rgba(255,0,0,0.8); 
    -webkit-box-shadow: inset 0 0 6px rgba(0,0,0,0.5); 
}
::-webkit-scrollbar-thumb:window-inactive {
	background: rgba(255,0,0,0.4); 
}