Why are my flex items not wrapping?

Question

So I have added 3 images within their own flex-item divs, and they all sit inside a flex-container div, the images scale as I make the browser window smaller, however they all remain inline rather than wrapping and becoming a single column, any idea on how to make them wrap?. This is how it looks:

div class="intro">
    <section id="intro-box">
      <h2>In a nutshell</h2>
      <p>Santorini is one of the Cyclades islands in the Aegean Sea belonging to Greece. It boasts masses of breathtaking cliffs rising over 300m from a submerged caldera. One of the of the most sizeable volcanic eruptions in recorded history happened
        in the island about 3,600 years ago – the Minoan eruption, it occurred at the height of the Minoan civilization.</p>
      <p>Santorini is famous for its dramatic views, spectacular sunsets, peculiar white aubergines and the beautiful town of Thira. The island pulls in circa 1.5 million tourists annually which all flock to experience the stunning panoramas and volcanic-sand
        beaches.
      </p>
      <div class="flex-container">
        <!--Photo from: www.santorinicrystalblue.com -->
        <div class="flex-item"><img class="img-fluid" src="media/sontorini-greece.jpg"></div>
        <!--Photo from: www.static2.traveltek.net -->
        <div class="flex-item"><img class="img-fluid" src="media/santorini-view-1.jpg"></div>
        <!--Photo from: www.mylossantorini.com-->
        <div class="flex-item"><img class="img-fluid" src="media/santorini-restaurant.jpg"></div>
      </div>
    </section>
  </div>
</main>

This is the CSS:

    /* Flexbox */

.intro .flex-container {
  width: 100%;
  display: flex;
    flex-direction: row;
    justify-content: center;
    flex-wrap: wrap;
}

.intro .flex-item {
  width: 30%;
  flex-direction: column;
}

.intro .img-fluid {
  width: 90%;
  padding: 2rem 0rem 2rem 0rem;
} 

Thanks in advance!

Answer 1

You need to use a media query to change the width of .flex-item. Unless you do this, it will always make them 30% of the window so they'll never wrap.

I included an example where I replaced your images with some stock images and included a media query to make it wrap at 600px.

  /* Flexbox */

.intro .flex-container {
  width: 100%;
  display: flex;
    flex-direction: row;
    justify-content: center;
    flex-wrap: wrap;
}

.intro .flex-item {
  width: 30%;
  flex-direction: column;
}

.intro .img-fluid {
  width: 90%;
  padding: 2rem 0rem 2rem 0rem;
} 

@media screen and (max-width:600px) {
  .intro .flex-item {
    width:50%;
  }
}

<div class="intro">
    <section id="intro-box">
      <h2>In a nutshell</h2>
      <p>Santorini is one of the Cyclades islands in the Aegean Sea belonging to Greece. It boasts masses of breathtaking cliffs rising over 300m from a submerged caldera. One of the of the most sizeable volcanic eruptions in recorded history happened
        in the island about 3,600 years ago – the Minoan eruption, it occurred at the height of the Minoan civilization.</p>
      <p>Santorini is famous for its dramatic views, spectacular sunsets, peculiar white aubergines and the beautiful town of Thira. The island pulls in circa 1.5 million tourists annually which all flock to experience the stunning panoramas and volcanic-sand
        beaches.
      </p>
      <div class="flex-container">

        <div class="flex-item"><img class="img-fluid" src="http://www.unsplash.it/400/300"></div>

        <div class="flex-item"><img class="img-fluid" src="http://www.unsplash.it/400/300"></div>

        <div class="flex-item"><img class="img-fluid" src="http://www.unsplash.it/400/300"></div>
      </div>
    </section>
  </div>