IssueTracker

UserAgent: Mozilla/5.0 (Macintosh; Intel Mac OS X 10_14_6) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/80.0.3987.87 Safari/537.36

Example URL:
https://codepen.io/visualjerk/pen/eYNNQEE

Steps to reproduce the problem:
1. Have a grid template like this:

```html
<div class="container">
  <div class="sidebar">
    <div class="sidebar__header">Sidebar header</div>
  </div>
  <div class="header">Header</div>
  <div class="content">Content</div>
</div>
```

```css
html, body {
  height: 100%;
  margin: 0;
}

.container {
  height: 100%;
  display: grid;
  grid-template-areas:
     'sidebar header'
     'sidebar content';
  grid-template-rows: auto minmax(1px, 1fr);
  grid-template-columns: auto 1fr;
}

.sidebar {
  grid-area: sidebar;
}

.sidebar__header {
  height: 200px;
  border: 1px solid green;
}

.header {
  grid-area: header;
}

.content {
  grid-area: content;
  border: 1px solid red;
}
```

What is the expected behavior?
The header area (class="header") should take the minimum required space for its content.

The content area (class="content) should fill the remaining height of its grid. So minmax(1px, 1fr) should result in 1fr in this scenario.

What went wrong?
The height of the header area is affected by the content of the sidebar area.

Does it occur on multiple sites: N/A

Is it a problem with a plugin? No

Did this work before? Yes 79

Does this work in other browsers? Yes

Chrome version: 80.0.3987.87  Channel: stable
OS Version: OS X 10.14.6
Flash Version: