Problem with :last-of-type:before

Problem with :last-of-type:before
0
#1

Hey, I’m really upset with this code, simple code but OMG i can’t solve this, trying to put a line between two buttons:

<style>
div.buttons{
  height: 50px;
  width: 100px;
  position: absolute;
  top: 0;
  right: 0;           
}
button{
  width: 50px;
  height: 50px;
  background: red;
  border: 0px;
  float: left;
  box-shadow: none; 
  outline: none;
}

button:last-of-type:before{
    content: ' ';
    width: 1px;
    height: 30px;
    position: absolute;
    top: 10px;
    left: 0;
    background: black;
}
</style>

 <div class="buttons">
      <button></button>
      <button></button>
 </div>
#2 
button {position: relative}
#3

Thank u so much, so simple!