How to span every 6th element full row, in a 3X3 grid in css?

I am setting up a 3 X N grid of images, that need to have a banner that spans the entire column in every 6,9th,... positions.

But while setting the span, I want the remaining white space to be filled.

I tried to add grid-auto-flow: dense but it does not put the images in the correct order.

Below is the code :

.grid { 
  display: grid;
  grid-template-columns: 1fr 1fr 1fr;
  grid-gap: 10px;
  align-items: start;
  justify-items: center;
  margin: auto;
  width: 540px;
  }
.grid img {
  border: 1px solid rgba(0,0,0,0.3);
  box-shadow: 2px 2px 6px 0px rgba(0,0,0,0.3);
  max-width: 100%;
}
.grid img:nth-child(6) {
  grid-column: span 3;
  }

<main class="grid">
  <img src="https://images.unsplash.com/photo-1533035353720-f1c6a75cd8ab?ixlib=rb-1.2.1&ixid=eyJhcHBfaWQiOjEyMDd9&auto=format&fit=crop&w=634&q=80" alt="Sample photo">
  <img src="https://images.unsplash.com/photo-1547149600-a6cdf8fce60c?ixlib=rb-1.2.1&ixid=eyJhcHBfaWQiOjEyMDd9&auto=format&fit=crop&w=634&q=80" alt="Sample photo">
  <img src="https://images.unsplash.com/photo-1533035353720-f1c6a75cd8ab?ixlib=rb-1.2.1&ixid=eyJhcHBfaWQiOjEyMDd9&auto=format&fit=crop&w=634&q=80" alt="Sample photo">
  <img src="https://images.unsplash.com/photo-1547149600-a6cdf8fce60c?ixlib=rb-1.2.1&ixid=eyJhcHBfaWQiOjEyMDd9&auto=format&fit=crop&w=634&q=80" alt="Sample photo">
  <img src="https://images.unsplash.com/photo-1533035353720-f1c6a75cd8ab?ixlib=rb-1.2.1&ixid=eyJhcHBfaWQiOjEyMDd9&auto=format&fit=crop&w=634&q=80" alt="Sample photo">
  <img src="https://images.unsplash.com/photo-1547149600-a6cdf8fce60c?ixlib=rb-1.2.1&ixid=eyJhcHBfaWQiOjEyMDd9&auto=format&fit=crop&w=634&q=80" alt="Sample photo">
  <img src="https://images.unsplash.com/photo-1555181937-efe4e074a301?ixlib=rb-1.2.1&ixid=eyJhcHBfaWQiOjEyMDd9&auto=format&fit=crop&w=634&q=80" alt="Sample photo">
  <img src="https://images.unsplash.com/photo-1547149600-a6cdf8fce60c?ixlib=rb-1.2.1&ixid=eyJhcHBfaWQiOjEyMDd9&auto=format&fit=crop&w=634&q=80" alt="Sample photo">
  <img src="https://images.unsplash.com/photo-1533035353720-f1c6a75cd8ab?ixlib=rb-1.2.1&ixid=eyJhcHBfaWQiOjEyMDd9&auto=format&fit=crop&w=634&q=80" alt="Sample photo">
  <img src="https://images.unsplash.com/photo-1547149600-a6cdf8fce60c?ixlib=rb-1.2.1&ixid=eyJhcHBfaWQiOjEyMDd9&auto=format&fit=crop&w=634&q=80" alt="Sample photo">
  <img src="https://images.unsplash.com/photo-1533035353720-f1c6a75cd8ab?ixlib=rb-1.2.1&ixid=eyJhcHBfaWQiOjEyMDd9&auto=format&fit=crop&w=634&q=80" alt="Sample photo">
</main>

Here is the codepen link : My Grid Example

I want to have a grid of images where each row is filled with just the 6,9th... images spanning across the columns. I don't want to get white spaces in between. Currently, I am getting white space in the 5th element.

How do I get it incorrect order and display it properly?

Solution

Just change your selector like this: .grid img:nth-child(7n + 7) {

It will select every 7n + 7 as the result first 6 elements will be 3 in row and next element will take 100% of the space