To set font size with pixels, use the px unit, with the font-size property. You can try to run the following code to set font size with pixels
Example
<!DOCTYPE html>
<html>
<head>
<style>
h1 {
font-size: 30px;
}
</style>
</head>
<body>
<h1>This is demo heading</h1>
<p>This is demo text.</p>
</body>
</html>Output
