Exemple de code de la fonction CSS drop-shadow().

<style>
.drop-shadow0{
 -webkit-filter : drop-shadow(0%); 
 filter         : drop-shadow(0%); 
}

.drop-shadow50{ 
 -webkit-filter  : drop-shadow(-8px -20px yellowgreen); 
 filter         : drop-shadow(-8px -20px yellowgreen); 
}

.drop-shadow100{
 -webkit-filter  : drop-shadow(5px 10px hsl(90,100%,49%)); 
 filter         : drop-shadow(5px 10px hsl(90,100%,49%)); 
}

.drop-shadow150{
 -webkit-filter  : drop-shadow(5px 1em 6px rgba(191,170,143,0.35) ); 
 filter         : drop-shadow(5px 1em 6px rgba(191,170,14,30.35) ); 
}

.img{ margin:10px }

</style>
<div style="width:150px; height:150px" class="img"><img src="/img/exemple/filter-image.jpg"></div>
<img src="/img/exemple/filter-image.jpg" style="width:150px; height:150px" class="img drop-shadow0"> 
<img src="/img/exemple/filter-image.jpg" style="width:150px; height:150px" class="img drop-shadow50">  
<img src="/img/exemple/filter-image.jpg" style="width:150px; height:150px" class="img drop-shadow100"> 
<img src="/img/exemple/filter-image.jpg" style="width:150px; height:150px" class="img drop-shadow150">