JSFiddle - React, Tailwind, and code Playground

HTML

<select id="sitestyle" name="stil">
            <option value="blue">Blå</option>
            <option value="green">Grön</option>
            <option value="red">Röd</option>
            <option value="pink">Rosa</option>                
        </select>

JavaScript

if(localStorage.style){
    document.getElementById("sitestyle").value = localStorage.style;
}
document.getElementById("sitestyle").onchange = function(){
     localStorage.style = this.value;  
}