Make sure to include position relative
in your .wrapper
since you are using postion: absolute
in the .blur
class.
.container {background-color: maroon;
border: 1px solid #dfe0e3;
border-radius: 10px;
overflow: hidden;
display: flex;
flex-direction: row;
justify-content: center;
margin: calc(20px/ 2) auto;
min-height: calc(40vh - 20px);
height: auto;
font-size: 50px;
position: relative;
}
.blur {
-webkit-backdrop-filter: blur(5px);
backdrop-filter: blur(5px);
background-color: #000000;
opacity: 0.5;
width: 100%;
position: absolute;
box-sizing: content-box;
z-index: 4;
border-radius: 15px;
height: 90%;
}
<div class="container"><div class="blur"></div>fdskfjdksfjfjklsdjfkdls Lorem ipsum dolor sit amet consectetur adipisicing elit. Aut minus error earum excepturi hic reiciendis officia libero molestias magni voluptas? Quidem aperiam perferendis consequuntur vero atque ipsum sed voluptate optio.</div>