To add transparency to a button, use the CSS opacity property. This creates a disabled look for the button.
You can try to run the following code to add transparency to a button
Example
<!DOCTYPE html>
<html>
<head>
<style>
.btn1 {
color: black;
text-align: center;
font-size: 15px;
}
.btn2 {
color: black;
text-align: center;
font-size: 15px;
opacity: 0.8;
}
</style>
</head>
<body>
<h2>Result</h2>
<p>Click below for result:</p>
<button class = "btn1">Enabled</button>
<button class = "btn2">Disabled</button>
</body>
</html>