Свойство text-stroke

text-stroke: text-stroke-width || text-stroke-color;

<!DOCTYPE html>
<html lang='ru'>
<head>
<meta charset='UTF-8'>
<meta name='viewport' content='width=device-width, initial-scale=1.0'>
<title>Document</title>
</head>
<body>
<style>
 #test {
 background-color: black;
 padding: 15px;
 color: white;
 }
 #hh {
 font: bold Arial;
 -webkit-text-stroke: 1px turquoise;
 color: transparent;
 animation: neon 2s linear infinite alternate-reverse;
 }
 @keyframes neon {
 from {
 -webkit-text-stroke: 1px turquoise;
 }
 to {
 -webkit-text-stroke: 1px coral;
 }
 }
 </style>
 <div id='test'>
 <h2 id='hh'>W E B I K</h2>
 </div>
</body>
</html>