f(input.id == "signup_email") {
          input.placeholder = "you@example.com";
        } else {
          input.placeholder = "";
        }
      }
    }, 3000);
  };
  
  function validate() {
    var isValid = true;
    
    for(var i = 0; i < form.elements.length; ++i) {
      var input = form.elements[i],
          allDivs = input.parentNode.getElementsByTagName("div");

      if(input.className.indexOf("required") >= 0) {
        if(input.id == "signup_email") {
          if(!email.test(input.value))