Generic Syntax Highlighter

<!-- comment -->
<div class="foo" id="bar" title="foo \"bar \\\" ba\'z qux">
  <p>lorem ipsum &amp; dolor sit</p>
</div>

<!DOCTYPE html>
<html dir="ltr">
  <head>
    <!-- comment -->
    <title>Test</title>
    <style>
    #foo {color:red}
    .bar {color:#fff}
    </style>
    <?php

    # do header ...
    echo do_header($_GET['foo']);

    ?>
  </head>
  <body>
    <script>
    // inline comment
    function foo(bar) {
        var v = /\s 123 true function\//g;
        var w = "foo" + 4;
        var x = true;
        var y = 4 + 5 + 1.5 + .4;
        var z = `<div>
  <div></div>
</div>`;
        /**
         * block comment
         */
        return "string" + 'string' + "string \" str\'ing" + 'string \' str\"ing' + "" + '';
    }
    </script>
  </body>
</html>

<!-- Mixed HTML-PHP test -->
<div class="<?php echo $foo ? 'foo' : 'bar'; ?>" id="foo">
  <?php echo $bar; ?>
</div>

Currently not targeted for highlighting CSS syntax.