Untitled

<!DOCTYPE html>
<html>
    <head>

    </head>
    <body>
        <h1> izgled</h1>
        <form id="formular">
            <label>Tema</label>
            <input type="radio" name="tema" value="svetlo" id="svetla">svetlo
            <input type="radio" name="tema" value="tamno" id="tamno">nigga
            <br>
            <label1>velicina teksta</label1>
            <select id="velicina">
                <option value="10px">mala</option>
                <option value="20px">srednja</option>
                <option value="40px">velika</option>

            </select>
        </form>
        <p>ahdfkljahskjafhasfhlasfhffasfhasash</p>
        <p>dasflihasfkjhasfkuhdaskjfhdasfkjuhdsfkhasdkjfhfdaskh</p>
        <script>
            let telo= document.body
            let formular = document.forms.formular;

            formular.svrtlo.addEventListener("click",function(){
                telo.classList.remove("tamna");
                telo.classList.add("svetla");
            });
            formular.svrtlo.addEventListener("click",function(){
                telo.classList.remove("svetla");
                telo.classList.add("tamno");
            });
            formular.velicina.addEventListener("change",function(){
                telo.style.fontSize=formular.velicina.value;
            })
        </script>
    </body>
</html>