radon form

<script>
 var textarray = [
 "Question 1",
 "Question 2",
 "Question 3"
     // pas virgule aprés dernier champs du tableau //
];

function RndText() {
  var rannum= Math.floor(Math.random()*textarray.length);
    if(textarray[rannum]=="Question 1"){
        document.getElementById('select1').style.display="initial";
        document.getElementById('select2').style.display="none";
        document.getElementById('select3').style.display="none";
    } else if(textarray[rannum]=="Question 2"){
       document.getElementById('select1').style.display="none";
        document.getElementById('select2').style.display="initial";
        document.getElementById('select3').style.display="none";
    }else if (textarray[rannum]="Question 3"){
        document.getElementById('select1').style.display="none";
        document.getElementById('select2').style.display="none";
        document.getElementById('select3').style.display="initial";    } 
}
window.onload = function() { RndText();}


</script>

<style>
    .formpara{
        margin-top:100px;
    }
    
    #select1,#select2,#select3,select, label , input,button,.choixmultiple,.titre3{
         margin-left: 40px;
        display:block;
    }
    select{
        width: 200px;
    }
    .titre3{
    font-family: 'Cairo', serif,"verdana",sans-serif,cursive,monospace;

    }
    input[type="text"],button[type="submit"]{
        width:auto;
        height: auto;
    }
    button[type="submit"]{
        margin-top: 40px;
        background-color: cadetblue;
    }
    .formpara{
        display: block;
    }
    @media (max-width:800px){
     label , input,button,.choixmultiple,.titre3{
         margin-left: auto;
        display:block;
    }
    }
</style>
<link href="https://fonts.googleapis.com/css?family=Inconsolata" rel="stylesheet">
<div class="formpara">
<meta charset="utf-8"/>
<h2 class="titre3">Forum </h2>
<br/>
<form method="post">
<meta charset="utf-8"/>
<label for="question1">question 1 :</label>
<input type="text" required name="question1"/>
<br/>
<label for="question2">question 2 ?</label>
<input type="text" required name="question2"/>
<br/>
<div id="select1" class="choixmultiple">
<label for="choices">choix 1 ?</label>
<SELECT  required name="choices">
            <option value="valeur1"></option>
            <option value="valeur2"></option>
            <option value="valeur3"></option>
          </SELECT>
 </div>
<div id="select2" class="choixmultiple">
<label for="choices2">choix2 ?</label>
<SELECT  required name="choices2">
            <option value="valeur1"></option>
            <option value="valeur2"></option>
            <option value="valeur3"></option>
          </SELECT>
 </div>
<div id="select3" class="choixmultiple">
<label for="choices3">choix 3 .</label>
<SELECT  required name="choices3">
            <option value="valeur1"></option>
            <option value="valeur2"></option>
            <option value="valeur3"></option>
          </SELECT>
 </div>
        <br/>
            <button id="button"  type="submit" class="btn btn-default">Valider </button>

    </form>