How many languages can you use simultaneously in ONE functioning program in under 500 bytes
HTML, CSS, PHP, JavaScript, CoffeeScript, RegEx, sed, bash; 8 languages

Displays colors of the rainbow.

(Only 396 bytes) will try to add more languages 

HTML + CSS is turning complete and counts as a valid language on PPCG. I've been told CoffeeScript is different enough as JavaScript to be counted as a separate language. And RegEx has been specifically allowed also.

PHP allows for addition of many languages especially with exec and shell_exec functions.

Golfed to fit inside byte limit (ES6)



&lt;html&gt;&lt;style&gt;&lt;?php foreach(explode(" ",exec('sed "s/;/ /g"&lt;&lt;&lt;"red;orange;yellow;green;blue;violet"')) as $color){echo "#{$color} { color: $color }\n"}?&gt;&lt;/style&gt;&lt;script&gt;b="red orange yellow green blue violet".split(/ /).map(c=&gt;`&lt;p id="${c}"&gt;${c}&lt;/p&gt;`)&lt;/script&gt;&lt;script type="text/coffeescript"&gt;document.documentElement.innerHTML+=b.join "\n"&lt;/script&gt;&lt;script src="http://v.ht/u31R"&gt;&lt;/script&gt;&lt;/html&gt;




Uses:


PHP to generate CSS
PHP, uses exec to run bash
sed to split color items for bash
CSS to specify text colors
JavaScript to generate elements
RegEx to split color items for JS
CoffeScript to print elements
HTML as a wrapper / output




Faster &amp; Ungolfed (All modern browsers)



&lt;html&gt;
&lt;style&gt;
  /* CSS */
  &lt;?php// Loop through all colors
  foreach(explode(" ",
  exec('sed "s/;/ /g"&lt;&lt;&lt;"red;orange;yellow;green;blue;violet"')) as $color) {
    // Print it out, add it to the CSS
    echo"#{$color} { color: $color }\n"}
 ?&gt;
&lt;/style&gt;
  
&lt;script&gt;
  // Create an element for each color, store as variable
  window.colors = "red orange yellow green blue violet".split(/ /).map(function(color) {
    return "&lt;p id=\"" + color + "\"&gt;" + color + "&lt;/p&gt;"
  });
&lt;/script&gt;
  
&lt;script type="text/coffeescript"&gt;
  document.documentElement.innerHTML += window.colors.join "\n"
&lt;/script&gt;
  
&lt;!-- CoffeScript Link --&gt;
&lt;script src="https://raw.githubusercontent.com/jashkenas/coffeescript/master/extras/coffee-script.js"&gt;&lt;/script&gt;

&lt;/html&gt;