I have a long list with sub-items which fall into the same category , wordpress

Question

I have a long list with subitems which fall into the same category. As the submenu is growing, I want the submenu to break over in listing the sub menu items in 3 columns. Anybody out there knowing the trick how to do that?

see here illustrated my issue:

topmenu item
-submenu 1
-submenu 2
-submenu 3
-submenu 4
-submenu 5
-submenu 6
-submenu 7
-submenu 8
-submenu 9
-submenu 10
-submenu 11
-submenu 12
-submenu 13
-submenu 14
-submenu 15
-submenu 16
-submenu 17
-submenu 18
-submenu 19
-submenu 20

I need it to be like this:

topmenu item
-submenu 1   -submenu 6   -submenu 11
-submenu 2   -submenu 7   -submenu 12
-submenu 3   -submenu 8   -submenu 13
-submenu 4   -submenu 9   -submenu 14
-submenu 5   -submenu 10  -submenu 15

Thanks

Answer 1

You could use flexbox to do this

5 items demo | 10 items demo | 15 items demo

MArkup

<div class="container">
    <div class="item">1</div>
    <div class="item">2</div>
    <div class="item">3</div>
    <div class="item">4</div>
    <div class="item">5</div>
    <div class="item">6</div>
    <div class="item">7</div>
    <div class="item">8</div>
    <div class="item">9</div>
    <div class="item">10</div>
    <div class="item">11</div>
    <div class="item">12</div>
    <div class="item">13</div>
    <div class="item">14</div>
    <div class="item">15</div>
</div>

CSS

.container{
    max-height: 200px;
    width: 100%;
    display: flex;
    flex-direction: column;
    flex-wrap: wrap;
    color: #fff;
    justify-content: flex-start;
    align-content: flex-start;
    align-items: flex-start;
}

.item{
      height: 20px;
      background: maroon;
      width: 200px;
      margin: 3px;
      padding: 5px;
}