Try it Live

<!DOCTYPE html>
<html>
<head>
    <style>
        h3 {
           position:relative;
           text-align:center;
           font-size:2em;
           -webkit-animation-name:text-animation-val;
           animation-name:text-animation-val;
           -webkit-animation-duration:5s;
           animation-duration:2s;
           animation-iteration-count:infinite;
        }
        
        @-webkit-keyframes text-animation-val {
          0%   {font-size:3em; text-shadow: 4px 4px 2px rgba(0,0,0,0.8);}
          30%  {font-size:4em; text-shadow: 3px 4px 2px rgba(255,28,28,1);}
          60%  {font-size:5em; text-shadow: 3px -5px 4px rgba(28,59,255,1);}
          100% {font-size:6em; text-shadow: 0px 7px 3px rgba(70,179,24,1);}
        }
        
        @keyframes text-animation-val {
          0%   {font-size:3em; text-shadow: 4px 4px 2px rgba(0,0,0,0.8);}
          30%  {font-size:4em; text-shadow: 3px 4px 2px rgba(255,28,28,1);}
          60%  {font-size:5em; text-shadow: 3px -5px 4px rgba(28,59,255,1);}
          100% {font-size:6em; text-shadow: 0px 7px 3px rgba(70,179,24,1);}
        }
    </style>
</head>
<body>
    <h3>Animation Text</h3>
</body>
</html>

​x
 
<!DOCTYPE html>
<html>
<head>
    <style>
        h3 {
           position:relative;
           text-align:center;
           font-size:2em;
           -webkit-animation-name:text-animation-val;
           animation-name:text-animation-val;
           -webkit-animation-duration:5s;
           animation-duration:2s;
           animation-iteration-count:infinite;
        }
        
        @-webkit-keyframes text-animation-val {
          0%   {font-size:3em; text-shadow: 4px 4px 2px rgba(0,0,0,0.8);}
          30%  {font-size:4em; text-shadow: 3px 4px 2px rgba(255,28,28,1);}
          60%  {font-size:5em; text-shadow: 3px -5px 4px rgba(28,59,255,1);}
          100% {font-size:6em; text-shadow: 0px 7px 3px rgba(70,179,24,1);}
        }
        
        @keyframes text-animation-val {
          0%   {font-size:3em; text-shadow: 4px 4px 2px rgba(0,0,0,0.8);}
          30%  {font-size:4em; text-shadow: 3px 4px 2px rgba(255,28,28,1);}
          60%  {font-size:5em; text-shadow: 3px -5px 4px rgba(28,59,255,1);}
          100% {font-size:6em; text-shadow: 0px 7px 3px rgba(70,179,24,1);}
        }
    </style>
</head>
<body>
    <h3>Animation Text</h3>
</body>
</html>
​