<style> .multicol-a { width: 300px; column-width: 100px; column-gap: 0; height: 100px; } .multicol-b { border: 1px solid silver; width: 200px; column-width: 51px; column-gap: 0; height: 50px; } .step { height: 1px; } .float-L { width: 1px; height: 1px; float: left; } .float-R { width: 1px; height: 26px; /* 25 -> 26 crash */ } </style> <div class="multicol-a"> <div class="float-R"></div> <div class="multicol-b"> <div class="step"></div> <div> <div class="float-L"></div> <div> </div> </div>