JSFiddle - React, Tailwind, and code Playground

HTML

<body>									 																				
    <div class="block1">
    </div><!--end block1--> 
    
    <div  class="block2 ">
    Как сделать тут прозрачный фон?
    </div><!--end block2-->  
    
    <div class="block1">
    </div><!--end block1--> 
    
    <div  class="block2 ">
    И как сделать тут прозрачный фон?
    </div><!--end block2-->
    
    <div class="block1">
    </div><!--end block1--> 
</body>

CSS

html, body {
	height: 100%;
}
.block1 {
	width: 100%;
	height:100%;
	background: url('http://oboi-dlja-stola.ru/file/11616/760x0/16:9/%D0%9C%D0%BE%D1%80%D0%B5-%D0%B8-%D0%BD%D0%B5%D0%B1%D0%BE.jpg') no-repeat top center;
	background-attachment: fixed;
	-moz-background-size: cover;
	-o-background-size: cover;
	-webkit-background-size: cover;
	background-size: cover;
}
.block2 {
	min-height: 500px;
}