Firefox fallback to css filters -webkit-filter: drop-shadow(12px 12px 7px rgba(0,0,0,0.5)); filter: url(shadow.svg#drop-shadow);

drop-shadow

<svg height="0" xmlns="http://www.w3.org/2000/svg">
 <filter id="drop-shadow">
    <feGaussianBlur in="SourceAlpha" stdDeviation="2.2"/>
    <feOffset dx="12" dy="12" result="offsetblur"/>
    <feFlood flood-color="rgba(0,0,0,0.5)"/>
    <feComposite in2="offsetblur" operator="in"/>
    <feMerge>
      <feMergeNode/>
      <feMergeNode in="SourceGraphic"/>
    </feMerge>
  </filter>
</svg>

Wow! Thank you!