Answers for "div screen size"

how to specify css for smaller screen

@media only screen and (max-width: 991px) and (min-width: 769px){
 /* CSS that should be displayed if width is equal to or less than 991px and larger 
  than 768px goes here */
}

@media only screen and (max-width: 991px){
 /* CSS that should be displayed if width is equal to or less than 991px goes here */
}

width in % of a screen css

1vw = 1% of viewport width
1vh = 1% of viewport height