Viewport units are values you can use in your CSS to size elements. 1 viewport unit is equivalent to 1% of a viewport dimension. There are four viewport units that you can use in your CSS: vw, vh, vmin and vmax.
1vwis 1% of the width of the viewport.1vhis 1% of the height of the viewport.1vminis 1% of whichever is smaller, the width or the height of the viewport.1vmaxis 1% of whichever is larger, the width or the height of the viewport.
