Use the column-rule-width property to set the width of the rule between columns.
Example
You can try to run the following code to implement the column-rule-width property:
<!DOCTYPE html>
<html>
<head>
<style>
.demo {
column-count: 4;
column-gap: 50px;
column-rule-color: maroon;
column-rule-style: dashed;
column-rule-width: 5px;
}
</style>
</head>
<body>
<div class = "demo">
This is demo text. This is demo text. This is demo text. This is demo text.
This is demo text. This is demo text. This is demo text. This is demo text.
This is demo text. This is demo text. This is demo text. This is demo text.
This is demo text. This is demo text. This is demo text. This is demo text.
This is demo text. This is demo text. This is demo text. This is demo text.
This is demo text. This is demo text. This is demo text. This is demo text.
This is demo text. This is demo text. This is demo text. This is demo text.
</div>
</body>
</html>