Why is the background doing that weird

Question

The background repeats itsself on my phone, how is that working and how can i fix it
https://code.sololearn.com/Wb56j9H1t41v/?ref=app

Answer 1

html {
background:linear-gradient(50deg, #12faaf, #faaafa) no-repeat;
background-size:100vw 100vh;
}

/* try this */

Answer 2

viewport

Answer 3

thanks, but what exactly does vw and vh stand for?
.......width and
.......height