<style>
.bg-categories{
  position:relative;
  background-image:url('img/conf/DSC_5062.JPG'); 
  background-size:cover;
  background-position:center;
  background-repeat:no-repeat;
}

.bg-categories::before{
  content:"";
  position:absolute;
  inset:0;
  background:rgba(0,0,0,0.65); 
}

.bg-categories .container{
  position:relative;
  z-index:2;
}
</style>