/* Portfolio Section */
main {
  margin: 10em auto 5em;
  text-align: center;
  padding: 2rem;
  background: #f9f9f9;
  padding: 0 10%;
}
main h1 {
  margin: 2em auto;
}
.portfolio-grid {
  display: grid;
  grid-template-columns: repeat(auto-fill, minmax(500px, 1fr));
  gap: 3em;
  grid-template-rows: masonry;
}
.portfolio-grid img {
  width: 100%;
  height: 100%;
  object-fit: cover;
  display: block;
  border-radius: 25px;
}
.portfolio-grid img:nth-child(3n) {
  grid-column: span 2;
}
.portfolio-grid img:nth-child(4n) {
  grid-row: span 2;
}

@media (max-width: 780px) { /* Tablette */
  .portfolio-grid {
    display: flex;
    flex-flow: row wrap;
  }
}