<form style="margin-top: 10px" id="formSend">
                    <input type="text" class="name" name="name" placeholder="Jméno" id="na" required="">
                    <input type="text" class="name" name="mail" placeholder="Email" id="em" required="">

                    <textarea placeholder="Vaše zpráva" id="ms" required=""></textarea>
                    <input type="submit" id="btn1" style="float: right;" value="SEND MESSAGE">
                </form>



        jQuery(document).ready(function ($) {
            $(".scroll").click(function (event) {
                event.preventDefault();
                $('html,body').animate({ scrollTop: $(this.hash).offset().top }, 1000);
            });

            $("#reserve-button").click(function () {
                $("#sl").trigger("click");
            });

               $("#more-button").click(function () {
                $("#more").toggle();
                if($.trim($("#more-button").text())=="Více")
                $("#more-button").text("Méně");
                else
                $("#more-button").text("Více");
            });

            $('#formSend').submit(function (e) {

// Prevent form submission which refreshes page
e.preventDefault();
});

            $('#btn1').click(function() {
    var val1 = $('#na').val();
    var val2 = $('#em').val();
    var val3 = $('#ms').val();

   if(val1=="" || val2=="" || val3=="")
   {
       return;
   }
    $.ajax({
        type: 'POST',
        url: 'mail.php',
        data: { text1: val1, text2: val2, text3: val3 },
        success: function(response) {
           alert("Odesláno");
        }
    });
});

        });