To create the most common masonry layout, your columns will be the grid axis and the rows the masonry axis. Define this layout with grid-template-columns and grid-template-rows:

.container {
  display: grid;
  gap: 10px;
  grid-template-columns: repeat(auto-fill, minmax(120px, 1fr));
  grid-template-rows: masonry;
}

The child elements of this container will now lay out item by item along the rows, as they would with regular grid layout automatic placement. However, as they move onto a new row the items will display according to the masonry algorithm. Items will load into the column with the most room causing a tightly packed layout without strict row tracks.

It is also possible to create a masonry layout with items loading into rows.

On the grid axis, things will work just as you expect them to in grid layout. You can cause items to span multiple tracks while remaining in auto-placement, using the span keyword. Items may also be positioned using line-based positioning.

In this example two of the items span two tracks, and the masonry items work around them.

This example includes an item which has positioning for columns. Items with definite placement are placed before the masonry layout happens.

The masonry axis operates under different rules as it is following the masonry layout rules rather than normal grid auto-placement rules. To control this axis we have three additional properties defined in the Grid Level 3 specification align-tracks, justify-tracks, and masonry-auto-flow.

The masonry-auto-flow property gives you a way to change how the masonry algorithm behaves. Give it a value of next and items will display in order on the grid axis, rather than going into whichever track has the most free space. The value positioned will ignore items with definite placement and place items in order-modified document order.

The align-tracks property allows for the alignment of items in grid containers with masonry in their block axis. The property aligns the items within their track, much in the way flex layout works. The property takes the same values as align-content, however you can specify multiple values to have different alignment values per track on the grid axis.

If you specify more values than tracks the additional values are ignored. If there are more tracks than values any additional tracks will use the last specified value.

The justify-tracks property works in the same way as align-tracks, however it is used when the masonry axis is the inline axis.

In browsers that do not support masonry, regular grid auto-placement will be used instead.

• Native CSS Masonry Layout In CSS Grid