I'm trying to drag elements along a line. They should push each other, not cross over or under.

To avoid having a shady element float around on drag, I drag a sub-div which then affects the position of the outer one. Works fine except when you release the mouse which triggers the last drag-event with `clientX` equal to `0` (see [CodePen](https://codepen.io/primavera133/pen/EKvbYV))!

```js
var b = document.querySelector('.box');
var bi = document.querySelector('.box-inner');
var b2 = document.querySelector('.box2');

bi.addEventListener('dragstart', function() {
  console.log("dragstart")
}, false);

bi.addEventListener('drag', function(event) {
  const bLeft = event.clientX;
  const b2Left = b2.offsetLeft;
  b.style.left = bLeft + "px";
  if (b2Left - 50 <= bLeft) {
    b2.style.left = (bLeft + 50) + "px";
  }

  console.log("drag", event.clientX, event.target.offsetParent.offsetLeft, b2.offsetLeft);

}, false);

bi.addEventListener('dragend', function() {
  console.log("dragend")
}, false);
```

```css
.box {
  width: 50px;
  height: 50px;
  background-color: hotpink;
  position: absolute;
  top: 0;
  left: 0;
}

.box-inner {
  width: 100%;
  height: 100%;
}

.box2 {
  width: 50px;
  height: 50px;
  background-color: rebeccapurple;
  position: absolute;
  left: 200px;
  top: 0;
}
```

```html
<div class="box">
  <div class="box-inner" draggable="true"></div>
</div>

<div class="box2"></div>
```

Why is this and what can I do to avoid resetting it?