Hi all! I have a background image in my columns, now I want to add the following Custom Css, but can't figure out the right code. I have this, but it does nothing to my background image:

.col.boxed {
-webkit-transition: all 1s ease;
-webkit-filter: grayscale(1);
}
.col.boxed:hover { 
-webkit-transition: all 1s ease;
-webkit-filter: grayscale(0);
}