CSS ::after background not displaying

I'm trying to make a tick image display after div element. I tried several combinations of CSS properties, but I just can't seem to figure out how to do it properly.

Answers to similar questions didn't help me.

HTML:

<div class="link-input-container">
  <input class="link-input" placeholder="Zalijepi link ovdje..." type="text" class="url_input" name="url_input">
</div>

CSS:

.link-input {
  font-family: Courier New;
  font-size: 12px;
}

.link-input-container::after {
  display: block;
  content: "";
  width: 12px;
  height: 12px;
  background: transparent url('https://cdn0.iconfinder.com/data/icons/weboo-2/512/tick.png') no-repeat;
}

Fiddle: http://jsfiddle.net/mk3fauk5/