How to do a sticky footer and still be able to do scrollable flexbox content?

Question

I'm trying to achieve the sticky footer (flexbox version). However, I'm unable to find a working solution if I also want the ability to have scrollable content inside a flex: 1 div (which requires parents to have height: 100%).

Here's a fiddle to demonstrate the problem: https://jsfiddle.net/gfaqLh42/6/

As you can see, the red area is scrollable (with a min-height: 300px). Notice the footer is offscreen even though the viewport is not less than the red area's min-height + blue area.

Is there a way to do a sticky footer and still use flexbox flex: 1 with scrollable content?

Update

Here's another picture to represent the other big problem I face in trying to make this work:

Answer 1

Is there a way to do a sticky footer and still use flexbox flex: 1 with scrollable content?

Yes, and what you need is to use Flexbox all the way.

So instead of using min-height/height on article-1/card, change their CSS to this:

.article-1 {
  flex: 1;
  display: flex;
  min-height: 0;                     /*  added, i.a Firefox need this  */
}

.card {
  overflow: auto;
}

Note, I also remove some properties not needed, mainly as they were set to their defaults, and added some. And why the need of min-width, is well explained here:

• Why don't flex items shrink past content size?

Updated fiddle

Stack snippet

html, body{
  height: 100%;
  margin: 0;
  font-weight: bold;
}

.header {
  position: absolute;
  height: 40px;
  background-color: grey;
  z-index: 1;
  width: 100%;
}

.content {
  display: flex;
  flex-direction: column;
  height: 100%;  
  padding-top: 40px;
  box-sizing: border-box;            /*  added  */
}

.wrap {
  flex: 1;
  display: flex;
  flex-direction: column;
  min-height: 0;                     /*  added, i.a Firefox need this  */
}

.container {
  flex: 1;
  padding: 10px;
  box-sizing: border-box;            /*  added  */
  display: flex;
  flex-direction: column;
  min-height: 0;                     /*  added, i.a Firefox need this  */
}

.article-1 {
  flex: 1;
  display: flex;
  min-height: 0;                     /*  added, i.a Firefox need this  */
}

.card {
  overflow: auto;
}

.card-text {
  height: 2000px;
  width: 2000px;
  background-color: red;
}

.article-2 {
  flex: none;
  height: 40px;
  background-color: blue;
}

.footer {
  position: relative;
  height: 40px;
  background-color: grey;
}

<div class="header">Header</div>
<div class="content">

  <div class="wrap">
    <div class="container">
      <div class="article-1">
        <div class="card">
          <div class="card-text">
            scrollable flex: 1 div<br>
            1. scrollable<br>
            2. scrollable<br>
            3. scrollable<br>
            4. etc...
          </div>
        </div>
      </div>
      <div class="article-2">
        flex: none div
      </div>
    </div>
  </div>

  <div class="footer">Footer</div>
</div>

---

Updated based on a comment

If there is a need for the article-1 to have a minimum height, and to avoid absolute positioning on it, a minimum height could be set on content as well, to push the footer further down on smaller screens.

Updated fiddle 2

Stack snippet

html, body{
  height: 100%;
  margin: 0;
  font-weight: bold;
}

.header {
  position: absolute;
  height: 40px;
  background-color: grey;
  z-index: 1;
  width: 100%;
}

.content {
  display: flex;
  flex-direction: column;
  height: 100%;  
  min-height: 450px;                 /*  added  */
  padding-top: 40px;
  box-sizing: border-box;            /*  added  */
}

.wrap {
  flex: 1;
  display: flex;
  flex-direction: column;
  min-height: 0;                     /*  i.a Firefox need this  */
}

.container {
  flex: 1;
  padding: 10px;
  box-sizing: border-box;            /*  added  */
  display: flex;
  flex-direction: column;
  min-height: 0;                     /*  i.a Firefox need this  */
}

.article-1 {
  flex: 1;
  display: flex;
  min-height: 300px;                 /*  changed  */
}

.card {
  overflow: auto;
}

.card-text {
  height: 2000px;
  width: 2000px;
  background-color: red;
}

.article-2 {
  flex: none;
  height: 40px;
  background-color: blue;
}

.footer {
  position: relative;
  height: 40px;
  background-color: grey;
}

<div class="header">Header</div>
<div class="content">

  <div class="wrap">
    <div class="container">
      <div class="article-1">
        <div class="card">
          <div class="card-text">
            scrollable flex: 1 div<br>
            1. scrollable<br>
            2. scrollable<br>
            3. scrollable<br>
            4. etc...
          </div>
        </div>
      </div>
      <div class="article-2">
        flex: none div
      </div>
    </div>
  </div>

  <div class="footer">Footer</div>
</div>