El.style doesn't work

Question

Hi,
Why won't this code move my element?

window.onload = () =>{

function addTextEl(x){
let a = document.createElement('span');
a.innerHTML = '🔥'
document.body.appendChild(a)
a.style.left = x
}

addTextEl(0)
addTextEl(50)
}

I'm using basic HTML, CSS design, no changes at all.
This code produces the text in same location ALWAYS, (2 '🔥' always one by the other, even when I change x) why??

Answer 1

FF9900 I see that you added 'px'
Thanks!

Answer 2

FF9900 I deleted the CSS and its working.
What are the display: block, and body 'overflow: hidden'?