JSFiddle - React, Tailwind, and code Playground

HTML

<div class="main">
    <div class="bg_gradient"></div>
    <div class="content">
        content
    </div>
</div>

CSS

.html,body{
    margin:0px;
    
}
    
.main{
    position:relative;
    background: #bbb;
}
.bg_gradient{
    position:absolute;
    top:0px;
    bottom:0px;
    left:0px;
    right:0px;
    background: linear-gradient(to bottom, rgba(255,255,255,0) 0%, rgba(255,255,255,1) 100%);
    z-index:0;
}
.content{
    position:relative;
    margin:0px auto;
    width:600px;
    height:1000px;
    border:1px solid #000;
    z-index:1;
}