Setting 100% height of the screen

style.css

html, body {
  height:100vh; /* viewport height */
}

/*
The second method is using the vh unit. Surely you already know that to determine the "size"
of an element in CSS we can use units such as pixels, points, percentages or even em. But
maybe you have not heard about the vh and vw units. A vh unit (viewport height) is
equivalent to 1% of the height of the viewport (the total of the screen of the device that
shows our web). 1vh = 1% of the total screen, 100vh = 100%. As you may have guessed, the
unit vw is the equivalent for the width.
*/