how to make flex items scrollable with overflowing content, column

Question

I have a pen, that i mustered up. I have a panel-section with square divs inside it, with a column direction, but for some reason I cannot make that panel section scrollable to accommodate the divs inside with there heights. I tried overflow-y: auto, but it does not behave as it should. Right now the boxes just shrink into position.

.panel-section {
      flex-basis: 18vw;
      background-color: #BFFD19;
      padding-top: 15px;
      padding-left: 15px;
      padding-right: 30px;

      min-height: 0px;
      display: flex;
      flex-direction: column;
      .thumbnail-holder {
        margin-bottom: 15px;
        background-color: #6036AD;
        width: 95%;
        height: 160px;
      }
    }
  }

https://codepen.io/anon/pen/OzKKgy

the panel-section (to the right) and the boxes are thumbnail holder. I have read other articles on overflow, but those techniques didnt work for me.

Answer 1

To make the .panel-section scrollable, add overflow: auto to its rule.

And then, as a flex item's default flex-shrink value is 1, which means it is set to shrink to fit its parent, add flex-shrink: 0 the .thumbnail-holder, and they will keep their height.

Additionally, a fix, which i.a. Firefox need, is to set min-height: 0; on the .top-section, allowing it to be smaller than its content.

Note, to avoid a vertical scrollbar on the viewport, and easier see the scrollbar on .panel-section, I changed the inline style on the modal-content element to width:100% (% instead of vw).

Updated codepen

Stack snippet

.modal-content {
  display: flex;
  flex-direction: column;
}
.modal-content .top-section {
  background-color: #2EC55C;
  flex-grow: 1;
  min-height: 0;
  display: flex;
}
.modal-content .top-section .content-section {
  flex-grow: 1;
  background-color: #6733FC;
  display: flex;
  flex-direction: column;
}
.modal-content .top-section .content-section .title-section {
  background-color: #21DE71;
  flex-basis: 10vh;
}
.modal-content .top-section .content-section .beer-section {
  background-color: #FA64FF;
  flex-grow: 1;
  display: flex;
}
.modal-content .top-section .content-section .beer-section .image-section {
  background-color: #90FF00;
  flex-basis: 50%;
  display: flex;
  align-items: center;
  justify-content: center;
}
.modal-content .top-section .content-section .beer-section .image-section .image-container {
  background-color: #FBA02B;
  height: 72vh;
  width: 55vh;
}
.modal-content .top-section .content-section .beer-section .text-section {
  background-color: #F63333;
  flex-basis: 50%;
}
.modal-content .top-section .panel-section {
  flex-basis: 18vw;
  background-color: #BFFD19;
  padding-top: 15px;
  padding-left: 15px;
  padding-right: 30px;
  min-height: 0px;
  display: flex;
  flex-direction: column;
  overflow: auto;
}
.modal-content .top-section .panel-section .thumbnail-holder {
  margin-bottom: 15px;
  background-color: #6036AD;
  width: 95%;
  height: 160px;
  flex-shrink: 0;
}
.modal-content .bottom-section {
  background-color: #4283FA;
  flex-basis: 10vh;
}
@media (max-width: 1100px) {
  .modal-content .top-section .panel-section {
    flex-basis: 25vw;
  }
}
@media (max-width: 450px) {
  .modal-content .top-section .panel-section {
    display: none;
  }
}

<div class="modal-content" style="height:100vh;width:100%;">
  <div class="top-section">
    <div class="content-section">
      <div class="title-section">

      </div>
      <div class="beer-section">
        <div class="image-section">
          <div class="image-container">

          </div>
        </div>
        <div class="text-section">

        </div>
      </div>
    </div>
    <div class="panel-section">
      <div class="thumbnail-holder">
      </div>
      <div class="thumbnail-holder">
      </div>
      <div class="thumbnail-holder">
      </div>
      <div class="thumbnail-holder">
      </div>
      <div class="thumbnail-holder">
      </div>
    </div>
  </div>
  <div class="bottom-section">

  </div>
</div>