How do I keep two side-by-side divs the same height?

Question

I have two divs side by side. I'd like the height of them to be the same, and stay the same if one of them resizes. I can't figure this one out though. Ideas?

To clarify my confusing question, I'd like both boxes to always be the same size, so if one grows because text is placed into it, the other one should grow to match the height.

Answer 1

Flexbox

With flexbox it's a single declaration:

.row {
  display: flex; /* equal height of the children */
}

.col {
  flex: 1; /* additionally, equal width */
  
  padding: 1em;
  border: solid;
}

<div class="row">
  <div class="col">Lorem ipsum dolor sit amet, consectetur adipisicing elit.</div>
  <div class="col">Lorem ipsum dolor sit amet, consectetur adipisicing elit. Ad omnis quae expedita ipsum nobis praesentium velit animi minus amet perspiciatis laboriosam similique debitis iste ratione nemo ea at corporis aliquam.</div>
</div>

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