Use the columnRuleWidth property to set the width between columns. You can try to run the following code to set the width of the rule between columns with JavaScript −
Example
<!DOCTYPE html>
<html>
<head>
<style>
#myID {
column-count: 4;
column-rule: 4px solid yellow;
}
</style>
</head>
<body>
<p>Click below to change width</p>
<button onclick="display()">Change Width between Columns</button>
<div id="myID">
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>
<script>
function display() {
document.getElementById("myID").style.columnRuleWidth = "8px";
}
</script>
</body>
</html>