JSFiddle - React, Tailwind, and code Playground

HTML

<div id="seconds">60</div>

CSS

#seconds { margin: 20px; font-size: 20px; }

JavaScript

$.fx.step.textShadowBlur = function(fx) {
        $(fx.elem).css({textShadow: '0 0 ' + Math.floor(fx.now) + 'px black'});
    };
    

setInterval(function() {
    
    $("#seconds").animate({textShadowBlur:20}, {duration: 300, complete: function() { 
        $("#seconds").animate({textShadowBlur:0}, {duration: 300}); 
    }});
}, 1000);