Cover image trick for a simple landing page, using simple css trick.
body {
font-family: Arial, Helvetica, sans-serif;
background: #333;
color: #fff;
margin: 0;
}
header {
display: flex;
flex-direction: column;
justify-content: center;
align-items: center;
text-align: center;
height: 100vh;
}
header:before {
content: '';
background: url('https://source.unsplash.com/1600x900/?nature,water') no-repeat center center/cover;
opacity: 0.6;
position: absolute;
top: 0;
left: 0;
width: 100%;
height: 100%;
z-index: -1;
}