html {
background: url("https://img4.goodfon.com/wallpaper/nbig/2/39/tokho-toukhou-devushka-fon-mech.jpg") no-repeat center center fixed;
-webkit-background-size: cover;
-moz-background-size: cover;
-o-background-size: cover;
background-size: cover;
}
.card {
opacity: 0.9;
}
.blurry {
backdrop-filter: blur(7px) !important;
}
pre code {
background-color: #eee;
border: 1px solid #999;
display: block;
padding: 20px;
}