viewport-percentage-image-size.html

<!DOCTYPE HTML>
<style>
img         { margin-top: 10px;}
#image-vw   { width: 2vw; height: 3vw; }
#image-vh   { width: 3vh; height: 4vh; }
#image-vmin { width: 4vmin; height: 5vmin; }
</style>

<div style="width:500px; height:500px">
    <img id="image-vw" src="./resources/colorsquare.png">
    <img id="image-vh"  src="./resources/colorsquare.png">
    <img id="image-vmin" src="./resources/colorsquare.png">
</div>

chromium/third_party/blink/web_tests/css3/viewport-percentage-lengths/viewport-percentage-image-size.html