<div class="bgdiv“ style="background-image: url('../test.png'); background-repeat: no-repeat; background-size: cover;">
<div style="position: inherit; z-index: 10;">文字部分</div>
</div>
.bgdiv{
height:100%;
position: relative;
background: inherit;
padding:1px;
box-sizing:border-box;
z-index:1;
}
.bgdiv::after{
content: "";
width:100%;
height:100%;
position: absolute;
left:0;
top:0;
background: inherit;
filter: blur(3px);
z-index: 2;
}