<style>
    div.test {
        width: 100px;
        height: 100px;
        -webkit-writing-mode: vertical-rl;
        -webkit-columns: 2;
        -webkit-column-rule: 50px solid orange;
        -webkit-column-gap: 50px;
        -webkit-column-fill: auto;
        columns: 2;
        column-rule: 50px solid orange;
        column-gap: 50px;
        column-fill: auto;
    }

    div.test div { width: 200px; }
</style>
<div class="test" style="border-block-start: 50px solid blue;"><div></div></div>
<div class="test" style="border-block-end: 50px solid blue;"><div></div></div>
