To bi trebalo štimat. Jedino ako tema koju koristiš nema neki jači body koji gazi to što si ubacio. To
ćeš vidjeti u devtools. Probaj i sa "!important".
Code:
<!DOCTYPE html>
<html lang="en">
<head>
<meta charset="utf-8">
<meta name="viewport" content="width=device-width, initial-scale=1">
<title>HTML5 Boilerplate</title>
<style>
body {
margin: 20px;
padding: 50px;
font-size: 1rem;
/*background: var(--bg);*/
box-shadow: inset 10px 0 90px #f4cfae !important;
font-family: "Fraunces", Georgia, serif;
font-variation-settings: "wght" 300;
font-weight: 400;
}
</style>
</head>
<body>
<h1>Page Title</h1>
</body>
</html>