.intro {
    background: -webkit-gradient(linear, left top, left bottom, from(rgba(0, 0, 0, 0.45)), to(rgba(0, 0, 0, 0))), url(../img/intro-bg-summer.jpg) center/cover no-repeat;
    background: -o-linear-gradient(top, rgba(0, 0, 0, 0.45) 0%, rgba(0, 0, 0, 0) 100%), url(../img/intro-bg-summer.jpg) center/cover no-repeat;
    background: linear-gradient(180deg, rgba(0, 0, 0, 0.45) 0%, rgba(0, 0, 0, 0) 100%), url(../img/intro-bg-summer.jpg) center/cover no-repeat;
}