What are the equivalent pixel values for $.$em and $.$rem elements?

html $\{$

font$-$size: $10$px;

$\}$

body $\{$

font$-$size: $2$rem;

$\}$

$.$rem $\{$

font$-$size: $1\mathrm{.}5$rem;

$\}$

$.$em $\{$

font$-$size: $2$em;

$\}$