[Dilettante_Pro]

С селектором

<style>
div {
  display: inline-block;
  width: 100px;
  height: 100px;
  margin: 20px;
  text-align: center;
  line-height: 100px;
}
.block-1 {
  box-shadow: 1px 12px 19px gray;
  height: 100px;
}
.block-2 {
  box-shadow: 1px 12px 19px gray;
  height: 100px;
}
.block-11 {
  box-shadow: 0px 2px 30px gray;
  height: 100px;
}
.block-101 {
  box-shadow: 1px 20px 90px gray;
  height: 100px;
}
.block-301 {
  box-shadow: 10px 2px 190px gray;
  height: 100px;
}
.content {
  display: block;
  display: flex;
  display: -webkit-flex;
  width: 96%;
  height: 150px;
  background: #fafafa;
}
.block-select {
  border: 0;
  outline: none;
}
</style>
<div class="content">
<p>
<select size="6" multiple class="block-select">
<option disabled>Выберите блок</option>
<option>block-1</option>
<option selected>block-2</option>
<option>block-11</option>
<option>block-101</option>
<option>block-301</option>
</select>
</p>
<div class="block-1">1</div>
<div class="block-2">2</div>
<div class="block-11">11</div>
<div class="block-101">101</div>
<div class="block-301">301</div>

</div>
<script>
[].forEach.call(document.querySelectorAll('.block-1'), function(node) {
	var bsh = getComputedStyle(node).boxShadow;
	node.style.boxShadow = "inset "+bsh;
});
document.querySelector('select').onchange = function() {
	var node = document.querySelector("." + this.value);
	    document.querySelector('.content').style.boxShadow = getComputedStyle(node).boxShadow;
 
};
</script>