(margin/padding)-right does not create space for overflow container

Question

For some reason, in an overflown container, the padding on the right side is not shown.

.parent {
  background-color: orange;
  width: 150px;
  height: 50px;
  overflow: auto; 
  padding-right: 15px;
}

.child {
  background-color: blue;
  width: 250px;
  height: 100%;
  margin: 0 10px;
}

body {
  margin: 0;
  padding: 0;
}

* {
  box-sizing: border-box;
}

<div class="parent">
  <div class="child">
  </div>
</div>

I expected the orange color to show up when I scrolled to the very end (right)

Answer 1

I have checked in also Mozilla Firefox. and it's working fine.

.parent {
  background-color: orange;
  width: 150px;
  height: 50px;
  overflow-y: hidden;
  overflow-x: auto;
  padding-right: 15px;
}

.child {
  background-color: blue;
  width: 250px;
  height: 100%;
  margin: 0 10px;
 display: inline-block;
}

body {
  margin: 0;
  padding: 0;
}

* {
  box-sizing: border-box;
}

<div class="parent">
  <div class="child">
  </div>
</div>

Answer 2

Let's start without applying any overflow property. We clearly have the element outside of it's parent container (add padding of the container will remain inside):

.parent {
  background-color: orange;
  width: 150px;
  height: 100px;
  padding:15px;
}

.child {
  background-color: blue;
  width: 250px;
  height: 100%;
}

body {
  margin: 0;
  padding: 0;
}

* {
  box-sizing: border-box;
}

<div class="parent">
  <div class="child">
  </div>
</div>

Now by adding overflow:scroll or overflow:auto you will simply add the scroll to see the overflowing part and you won't have the padding as excepted:

.parent {
  background-color: orange;
  width: 150px;
  height: 100px;
  overflow:auto;
  padding:15px;
}

.child {
  background-color: blue;
  width: 250px;
  height: 100%;
}

body {
  margin: 0;
  padding: 0;
}

* {
  box-sizing: border-box;
}

<div class="parent">
  <div class="child">
  </div>
</div>

Same logic with the margin right. When the element is overflowing there is no room to add margin between the inner element and the parent element.

Answer 3

You should use below CSS. It's working for me.

.parent {
    background-color: orange;
    width: 150px;
    height: 50px;
    padding-right: 15px;
    overflow-y: hidden;
    overflow-x: auto;
}
.child {
    background-color: blue;
    width: 250px;
    height: 100%;
    margin: 0 10px;
    display: inline-block;
}