JSFiddle - React, Tailwind, and code Playground

HTML

<div class="mydiv">
    <div class='bgblur'></div>
</div>
<div class="mydiv2">
    <div class='bgblur'></div>
</div>

CSS

body {
    background: url('http://hdwallpaperia.com/wp-content/uploads/2013/11/Space-Background-Wallpaper.jpg') no-repeat center center fixed;
    background-size: cover;
}

.bgblur {
    background: url('http://hdwallpaperia.com/wp-content/uploads/2013/11/Space-Background-Wallpaper.jpg') no-repeat center center fixed;
    background-size: cover;
    -webkit-filter: blur(26px);
    -moz-filter: blur(26px);
    
    position: absolute;
    height: 100%;
    width: 100%;
    z-index: -1;
}

.mydiv {
    border: 2px solid black;
    position: relative;
    overflow: hidden;
    height: 200px;
    width: 200px;
}

.mydiv2 {
    border: 2px solid black;
    position: absolute;
    left: 50px;
    top: 250px;
    overflow: hidden;
    height: 300px;
    width: 300px;
}