Chrome has bug in Rem Calculation?

Rem Calculation within 0.3125rem becomes wrong if we shouldn't gave default font-size for root element in Chrome

for example, In below code I haven't gave font-size for root element. so it takes default font-size 16px. Recording this, div element must take 4px (0.25rem) .but it took 6px.

But it could works fine, if rem will be exceed than 0.3125

html, body {
font-family: sans-serif
}
div {
font-size: 0.25rem
}
<div>font-size: 0.25rem</div>

If I gave font-size for root element, it works correctly. checkout below example

html, body {
  font-family: sans-serif;
  font-size: 16px;
}
div {
 font-size: 0.25rem
}
<div>font-size: 0.25rem</div>

Does anyone know the answer about this? If yes, please let me know