Anki -- Using Showdown and HighlightJS for a solution that works across both Anki Desktop and AnkiDroid (version 1)

anki-showdown-hljs-v1.html

<div class="front-content">
{{Front}}
</div>
<script>
function addStylesheet(src, callback) {
	var s = document.createElement('link');
	s.rel = 'stylesheet';
	s.href = src;
	s.onload = callback;
	document.head.appendChild(s);
}

function addScript(src, callback) {
    var s = document.createElement('script');
    s.src = src;
    s.type = "text/javascript";
    s.onload = callback;
    document.body.appendChild(s);
}
	
function replaceAllWhitespaceWithSpace(str) {
    return str.replace(/[\t\v\f \u00a0\u2000-\u200b\u2028-\u2029\u3000]/g, ' ');
}

addStylesheet('https://cdnjs.cloudflare.com/ajax/libs/highlight.js/9.15.5/styles/default.min.css', function() {

});
addScript('https://cdnjs.cloudflare.com/ajax/libs/showdown/1.9.0/showdown.min.js', function() {
	addScript('https://cdnjs.cloudflare.com/ajax/libs/highlight.js/9.15.5/highlight.min.js', function() {
        function processShowdownDivs() {
            var showdownConverter = new showdown.Converter();
            showdownConverter.setFlavor('github');
        
            document.querySelectorAll('div.front-content').forEach((div) => {
                var rawText = div.innerText;
                var text = replaceAllWhitespaceWithSpace(rawText);
                var html = showdownConverter.makeHtml(text);
                var newDiv = document.createElement('div');
                newDiv.innerHTML = html;
                newDiv.querySelectorAll('pre code').forEach((block) => {
                    hljs.highlightBlock(block);
                });
                div.parentNode.insertBefore(newDiv, div.nextSibling);
	     div.style.display = 'none';
            });
        };
        
        processShowdownDivs();
     });
});
</script>