<style>
    div { font-size: 20px; font-family: ahem; border: solid black; color: indigo; width: 25em; margin: 8px 0; -webkit-font-smoothing: none; }
    ruby { color: blue; }
    ruby rt { color: silver; }
</style>
<div>
<ruby>xx<rt>xxxxxxxx</rt></ruby>lllll<ruby>yy<rt>yyyyyyyy</rt></ruby>lllll<ruby>zz<rt>zzzzzzzz</rt></ruby>
</div>
<div>
<ruby>xx<rt>xxxxxxxx</rt></ruby><span style="font-size: 50%">ll</span><ruby>yy<rt>yyyyyyyy</rt></ruby><span style="font-size: 50%">ll</span><ruby>zz<rt>zzzzzzzz</rt></ruby>
</div>
<div>
<ruby>xx<rt>xxxxxxxx</rt></ruby><span style="font-size: 100%">ll</span><ruby>yy<rt>yyyyyyyy</rt></ruby><span style="font-size: 100%">ll</span><ruby>zz<rt>zzzzzzzz</rt></ruby>
</div>
<div>
<ruby>xx<rt>xxxxxxxx</rt></ruby><span style="font-size: 150%">ll</span><ruby>yy<rt>yyyyyyyy</rt></ruby><span style="font-size: 150%">ll</span><ruby>zz<rt>zzzzzzzz</rt></ruby>
</div>