#flasher {
	margin: 0px;
	padding: 0px;
	position: fixed;
	top: 0px;
	left: 0px;
	width: 100%;
	height: 100%;
	
	background-color: yellow;
    -webkit-animation-name: flashing;
    animation-name: flashing;
    -webkit-animation-duration: 0.5s; /* this is your speed value */
    animation-duration: 0.5s; /* this is your speed value */
	-webkit-animation-iteration-count: infinite;
	animation-iteration-count: infinite;
}

@keyframes flashing {
    0% {background-color: yellow;}
    45% {background-color: yellow;}
    50% {background-color: blue;}
    95% {background-color: blue;}
    100% {background-color: yellow;}
}
@-webkit-keyframes flashing {
    0% {background-color: yellow;}
    45% {background-color: yellow;}
    50% {background-color: blue;}
    95% {background-color: blue;}
    100% {background-color: yellow;}
}