css/css-values/ic-unit-004.html

<!DOCTYPE html>
<meta charset="utf-8">
<title>CSS Values and Units Test: the ic unit in vertical orientation</title>
<link rel="author" title="Florian Rivoal" href="http://florian.rivoal.net/">
<link rel="help" href="https://drafts.csswg.org/css-values-4/#font-relative-lengths">
<link rel="help" href="https://www.w3.org/TR/css-writing-modes-3/#block-flow">
<link rel="help" href="https://www.w3.org/TR/css-writing-modes-3/#text-orientation">
<link rel="match" href="reference/ic-unit-001-ref.html">
<meta name="assert" content="In vertical sideways, the ic unit is equal to the used horizontal advance measure of the 水 (CJK water ideograph, U+6C34) glyph found in the font used to render it.">
<style>
@font-face {
    font-family: IcTestFullWidth;
    src: url(resources/IcTestFullWidth.woff2);
}

span {
    font: 20px IcTestFullWidth;
    background: green;
    color: green;
    left: 0; right: 0;
    position: absolute;
}

div {
    font: 20px IcTestFullWidth;
    background: red;
    color: red;
    position: relative;
    height: 5ic;
    width: 10ic;
    writing-mode: vertical-rl;
    text-orientation: sideways;
}

div + div {
    height: auto;
}

div + div span {
    height: 5ic;
}
</style>
<body>
    <p>Test passes if there is a <strong>filled green square</strong> and <strong>no red</strong>.</p>
    <div><span>水水水水水</span></div>
    <div><span></span>水水水水水</div>
</body>