I usally assign root div a color and give it a color with min-height: 100vh (min-h-screen). But sometimes I need to use different style in a page. So if I make this child <div class="h-full">, it doesn't work. See this post.
I found this to be most reliable:
.parent {
/* min-h-screen */
min-height: 100vh;
}
.child {
/* min-h-[inherit] */
min-height: inherit;
}