If you are splitting your UL into a column format li in a similar way to the below:-

ul {width: 625px;max-width: 840px;min-height: 280px;list-style: none outside none;}li {float: left;position: relative;display: inline-block;width: 40%;padding: 0px;margin: 0px;}
.. what you might find is that if the li on either side is higher than the other that the corresponding li is overlapped or thrown out of place like so:-

‍

overlapping-li

The highlighted 3rd item should be starting a new line, but is being pushed to the right as the first li has a height taller than the second throwing the nested lis out of position. To unify the columns and force the li to a new line in the respective column we simply need to add the following CSS:-

‍NB If you have more than 2 columns simply amend the ('your column number'n+1) value.... and then you get:-

overlapping-li-1

Note that the li is pushed to a new line.We have found this technique extremely useful when adjusting menu items in the UberMenu plugin from Codecanyon.