I was trying to create Divs by clicking a button but it just fill the button range with red.
<div class="app">
<button onclick="createDiv()">Make a cube</button>
</div>
<script>
function createDiv ()
{
var boxEle = document.querySelector('.app');
boxEle.style.width = 100;
boxEle.style.height = 100;
boxEle.style.backgroundColor = '#f00';
}
</script>