The column-rule-style property specifies the style of the rule between columns.
column-rule-style: none|hidden|dotted|dashed|solid|double|groove|ridge|inset|outset|initial|inherit;
div { -webkit-column-rule-style: dotted; /* Chrome, Safari, Opera */ -moz-column-rule-style: dotted; /* Firefox */ column-rule-style: dotted; }