JSFiddle - React, Tailwind, and code Playground

HTML

<div id="scrollwrap">
    Stuff
    <br>
    <input value="1"  type="checkbox" name="salgsvilkar" ID="checkbox2"  style="float:left;"
    onClick="accept();" /><label for="checkbox2" class="akslabel">Salgs og leveringsvilkår er lest og akseptert</label>
</div>

CSS

#scrollwrap
{
    width:535px;
    height:100%;
    overflow:hidden;
    padding:5px;
    background-color:#F5D9D9;
    border: 1px solid #C22323;
    border-radius:5px;
    -moz-border-radius:5px;
    -webkit-border-radius:5px;
    padding-bottom:15px;
    margin-top:10px;
    
}

#highlight
{
    width:535px;
    height:100%;
    overflow:hidden;
    padding:5px;
    background-color:#E5F7C7;
    border: 1px solid #85c222;
    border-radius:5px;
    -moz-border-radius:5px;
    -webkit-border-radius:5px;
    padding-bottom:15px;
    margin-top:10px;
    
}

JavaScript

$(function accept() {
    $("div.#scrollwrap").attr('id','highlight');
});