CSS Grid Layout not working in IE11 even with prefixes

I'm using following HTML markup for my grid.

<section class="grid">
    <article class="grid-item width-2x height-2x">....</article>
    <article class="grid-item">....</article>
    <article class="grid-item">....</article>
    <article class="grid-item width-2x">....</article>
    <article class="grid-item height-2x">....</article>
    <article class="grid-item">....</article>
    <article class="grid-item">....</article>
    <article class="grid-item width-2x height-2x">....</article>
</section>

The SCSS code is something like below:

.grid {
    display: grid;
    grid-template-columns: repeat( 4, 1fr );
    grid-gap: 30px;
    align-items: start;

    .grid-item {
        &.height-2x {
            grid-row: span 2;
        }
        &.width-2x {
            grid-column: span 2;
        }
    }
}

Since I'm using auto-prefixer in my workflow it automatically adds all relevant properties with -ms prefix. I can confirm it via inspect element.

Now, the issue is this code works just fine in Chrome, Firefox and Opera, but when I open this page in Microsoft Edge or in IE 11 all grid items are overlapping each other at first cell. According to this site these browsers support CSS Grid layout with -ms prefix. I've created a CodePen for this scenario.

CodePen Link

Why is it not working?

.grid {
  display: -ms-grid;
  display: grid;
  -ms-grid-columns: (1fr)[4];
  grid-template-columns: repeat(4, 1fr);
  -ms-grid-rows: (270px)[4];
  grid-template-rows: repeat(4, 270px);
  grid-gap: 30px;
}

.grid .grid-item {
  background-color: #000;
  color: #fff;
  text-align: center;
  line-height: 270px;
}

.grid .grid-item.height-2x {
  -ms-grid-row: span 2;
  grid-row: span 2;
}

.grid .grid-item.width-2x {
  -ms-grid-column: span 2;
  grid-column: span 2;
}

<section class="grid">
  <article class="grid-item width-2x height-2x">....</article>
  <article class="grid-item">....</article>
  <article class="grid-item">....</article>
  <article class="grid-item width-2x">....</article>
  <article class="grid-item height-2x">....</article>
  <article class="grid-item">....</article>
  <article class="grid-item">....</article>
  <article class="grid-item width-2x height-2x">....</article>
</section>

Solution

IE11 uses an older version of the Grid specification.

The properties you are using don't exist in the older grid spec. Using prefixes makes no difference.

Here are three problems I see right off the bat.

`repeat()`

The repeat() function doesn't exist in the older spec, so it isn't supported by IE11.

You need to use the correct syntax, which is covered in another answer to this post, or declare all row and column lengths.

Instead of:

.grid {
  display: -ms-grid;
  display: grid;
  -ms-grid-columns: repeat( 4, 1fr );
      grid-template-columns: repeat( 4, 1fr );
  -ms-grid-rows: repeat( 4, 270px );
      grid-template-rows: repeat( 4, 270px );
  grid-gap: 30px;
}

Use:

.grid {
  display: -ms-grid;
  display: grid;
  -ms-grid-columns: 1fr 1fr 1fr 1fr;             /* adjusted */
      grid-template-columns:  repeat( 4, 1fr );
  -ms-grid-rows: 270px 270px 270px 270px;        /* adjusted */
      grid-template-rows: repeat( 4, 270px );
  grid-gap: 30px;
}

Older spec reference: https://www.w3.org/TR/2011/WD-css3-grid-layout-20110407/#grid-repeating-columns-and-rows

`span`

The span keyword doesn't exist in the older spec, so it isn't supported by IE11. You'll have to use the equivalent properties for these browsers.

Instead of:

.grid .grid-item.height-2x {
  -ms-grid-row: span 2;
      grid-row: span 2;
}
.grid .grid-item.width-2x {
  -ms-grid-column: span 2;
      grid-column: span 2;
}

Use:

.grid .grid-item.height-2x {
  -ms-grid-row-span: 2;          /* adjusted */
      grid-row: span 2;
}
.grid .grid-item.width-2x {
  -ms-grid-column-span: 2;       /* adjusted */
      grid-column: span 2;
}

Older spec reference: https://www.w3.org/TR/2011/WD-css3-grid-layout-20110407/#grid-row-span-and-grid-column-span

`grid-gap`

The grid-gap property, as well as its long-hand forms grid-column-gap and grid-row-gap, don't exist in the older spec, so they aren't supported by IE11. You'll have to find another way to separate the boxes. I haven't read the entire older spec, so there may be a method. Otherwise, try margins.

grid item auto placement

There was some discussion in the old spec about grid item auto placement, but the feature was never implemented in IE11. (Auto placement of grid items is now standard in current browsers).

So unless you specifically define the placement of grid items, they will stack in cell 1,1.

Use the -ms-grid-row and -ms-grid-column properties.