.bloc_login {
    background: url("../images/login_bg.jpg") no-repeat scroll 0 0 transparent;
    height: 350px;
    margin: 0 auto;
    padding: 95px 0 0 0;
    position: relative;
    top: 20%;
    width: 450px;
}
header #header_content
{
	background :  	url("../images/bg_header1.jpg") no-repeat bottom left ;
}
header
{
	background :  #fff	url("../images/bg_header2.jpg") no-repeat bottom right ;
}