background:linear-gradient( rgba(0, 0, 0, 0.5) 100%, rgba(0, 0, 0, 0.5)100%),url("logo/header-background.png");
/*You need to use the full property name for each: */
background-color: #6DB3F2;
background-image: url('images/checked.png');
background:linear-gradient(#000,#000),
linear-gradient(#000,#000),
url("https://cdn.shopify.com/s/files/1/0593/3452/5099/products/cover_1_1_1024x1024@2x.jpg?v=1631790248") !important;