css/css-values/ch-unit-001.html

<!DOCTYPE html>
<meta charset="utf-8">
<title>CSS Values and Units Test: support for the ch unit</title>
<link rel="author" title="Florian Rivoal" href="http://florian.rivoal.net/">
<link rel="help" href="https://drafts.csswg.org/css-values-3/#font-relative-lengths">
<link rel="match" href="reference/ch-unit-001-ref.html">
<meta name="assert" content="The ch unit is equal to the used advance measure of the 0 (ZERO, U+0030) glyph found in the font used to render it.">
<style>
span {
    background: green;
    color: green;
    top: 0; bottom: 0;
    position: absolute;
}
div {
    background: red;
    color: red;
    position: relative;
    height: 10ch;
    width: 5ch;
    float: left;
}

div + div {
    width: auto;
}

div + div span {
    width: 5ch;
}
</style>
<body>
    <p>Test passes if there is a <strong>filled green square</strong> and <strong>no red</strong>.</p>
    <div><span>00000</span></div>
    <div><span></span>00000</div>
</body>