<div class="minheight1">

</div>
<div class="minheight2">

</div>
<div class="minheight3">
  1 <br /> 2 <br />
</div>

<div class="minheight4">
  1 <br /> 2 <br />
</div>

* {
  margin: 10px;
}

.minheight1 {
  content: "";
  width: 50px;
  background-color: gold;
  height: 10px;
  max-height: 10px;
  min-height: 50px;
}

.minheight2 {
  content: "";
  width: 50px;
  background-color: blue;
  height: 50px;
  max-height: 10px;
  min-height: 10px;
}

.minheight3 {
  content: "";
  width: 50px;
  background-color: green;
  height: 20px;
  max-height: 50px;
  min-height: 10px;
}

.minheight4 {
  content: "";
  width: 50px;
  background-color: olive;
  max-height: 50px;
  min-height: 10px;
}