CSS Distribute li over 2 rows, unlimited items

Question

I want my li's to be distributed over 2 rows like this:

item 1    item 3    item 5    item 7    item 9    ....
item 2    item 4    item 6    item 8    ......

My CSS is really bad so I have no clue on how to achieve this and can't find anything on this... I tried some stuff with even and odd items, but I can't figure out how to force even items below odd items.

Answer 1

You can use flexbox to achieve this ordering. Support is pretty good (http://caniuse.com/#feat=flexbox) but you will need to provide fallbacks for older versions of IE.

ul {
    display: flex;
    flex-direction: column;
    flex-wrap: wrap;
    height: 100px;
    list-style-type: none;
    margin: 0;
    padding: 0;
    width:200px;
}
li {
    color: #000000;
    height: 50px;
    margin: 0;
    padding: 0;
    width: 100px;
}

<ul>
  <li>Item 1</li>
  <li>Item 2</li>
  <li>Item 3</li>
  <li>Item 4</li>
  <li>Item 5</li>
  <li>Item 6</li>
</ul>

Answer 2

You can use :nth-child selector to select odd elements in that list items.

Here is an example:

CSS

ul {
    position: relative;
    white-space: nowrap;
}
li {
    display: inline-block;
    list-style-type: none;
    padding: 0px 5px;
}
li:nth-child(2n) {
    top: 100%;
    position: absolute;
    margin-left: -36px;   /* Changes as per the width of the first element */
}

Working Fiddle