<form action="https://google.com/search" target="_blank" type="GET">

  <label>Search CSS-Tricks on Google: <input type="search" name="q"></label>
  <input type="submit" value="Go">

</form>
body {
  height: 100vh;
  margin: 0;
  display: grid;
  place-items: center;
}
View Compiled
var form = document.querySelector("form");

form.addEventListener("submit", function (e) {
  e.preventDefault();
  var search = form.querySelector("input[type=search]");
  search.value = "site:css-tricks.com " + search.value;
  form.submit();
});

External CSS

  1. https://s3-us-west-2.amazonaws.com/s.cdpn.io/3/mvp.css

External JavaScript

This Pen doesn't use any external JavaScript resources.