pls in the h1 {text-shadow:rgba(0,0,200,1) 1px 2px 5px 0.5em} i dnt really knw d fuction of that a. pls help me

Answer 1

"a" is the alpha-transparency (values from 0 (transparent) to 1 (opaque))

Answer 2

that's text-shadow to get shadow to do it color has been chosen transparent like black .
then
offset and y offset then blur of shadow and then spread are written