Same height columns

<div class="container">
<!-- Column -->
<div class="container__column">
<!-- Cover -->
...
<!-- Content -->
<div class="container__content">
...
</div>
<!-- Button sticks to the bottom -->
...
</div>
<!-- Repeat with other columns -->
...
</div>
.container {
display: flex;
}
.container__column {
flex: 1;
/* Space between columns */
margin: 0 8px;
/* Layout each column */
display: flex;
flex-direction: column;
}
.container__content {
/* Take available height */
flex: 1;
}