.bg {
background-image: url('../img/mount-sky.jpg');
opacity: 1;
background-repeat: no-repeat;
background-size: cover;
background-position: 50% 100%;
position: absolute;
top: 0;
left: 0;
right: 0;
bottom: 0;
width: 100%;
height: 100%;
z-index: 1;
}