<!DOCTYPE html>
<html>
<head>
<meta charset="UTF-8">
<style>
#a {
filter: brightness(1);
border-style: solid;
}
#b {
opacity: 0.2;
</style>
</head>
<body>
<span id="b">
<span id="a">
<div></div>
</span>
</body>
</html>