why is my css background image not showing?

Not too sure why, but it is showing up as a blank screen.

How it looks:

enter image description here

Here is my file structure:

enter image description here

css:

*{
    margin: 0;
    padding: 0;
    box-sizing: border-box;
}


html {
    background-color: #ffffff;
    color: #555;
    font-family: 'lato', 'Arial';
    font-weight: 300;
    font-size: 20px;
    text-rendering: optimizeLegibility;
}


.row{
    max-width: 1140px;
    margin: 0 auto;
}


header{
    background-image: url(/resources/css/images/hero.jpg);
}

HTML:

<!DOCTYPE html>
<html lang="en">
<head>
    <link rel="stylesheet" type="text/css" href="resources/vendors/css/normalize.css">
    <link rel="stylesheet" type="text/css" href="resources/vendors/css/grid.css">
    <link rel="stylesheet" type="text/css" href="resources/css/style.css">
    <link href="https://fonts.googleapis.com/css2?family=Lato:ital,wght@0,100;0,300;0,400;1,300&display=swap" rel="stylesheet">
    <meta charset="UTF-8">
    <meta name="viewport" content="width=device-width, initial-scale=1.0">
    <title>OmniFoods</title>

    <header>
        <div class="hero-text-box">
            <h1>Goodbye junk food. Hello super Healthy meals</h1>
            <a href="#">I’m hungry</a>
            <a href="#">Show me more</a>

        </div>
    </header>
</head>
<body>


</body>
</html>

I guess you are looking for this in wrong directory, beacuse your style is already in "resources/css/". Try to continue this directory by doing this:

header{
    background-image: url("./images/hero.jpg");
}