.border-button {
  box-shadow: 0px 0px 0px 5px #FC5185;
  transition: box-shadow 0.6s linear;
  margin: 0.5em; /* Increased margin since the box-shado expands outside the element, like outline */
}

.border-button:hover { box-shadow: 0px 0px 0px 10px #FC5185; }


div.boxheading
{
 background: #4CAF50;
  border: none;
  border-radius: 25px;
  color: snow; // Vanilla HTML color name;
  cursor: pointer;
  font-size: 1.25em;
  letter-spacing: .1em;
  outline: none;
  padding: .75em 2em;
  position: relative; // Required for pseudo-element positioning
  text-transform: uppercase;   
  }
  
  div.boxheading::before {
    background: #4CAF50;
    border-radius: inherit;
    content: '';
    filter: blur(10px); // Controls the extent of the initial glow
    opacity: .75;
    position: absolute;
    transition: all .3s ease-in-out;
    width: 100%;
    height: 100%;
    top: 0;
    right: 0;
    z-index: -1; // Set behind primary button
  }