* {margin: 0; padding: 0; box-sizing: border-box;}

p 
{
	border-radius: 5px;
	margin: 10px auto;
	width: 75%;
	padding: 5px;
}
p.valid 
{
	background-color: rgba(0,255,0,.5);
}
p.invalid 
{
	background-color: rgba(255,0,0,.5);
}