<meta charset="utf-8">
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    .test { margin: 8px 0; text-align: justify; border: solid; width: 100px; font-family: "hiragino mincho pro"; }
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<div>
    <div class="test">
        a. b. <span>i</span>はxxxxxxx
    </div>
    <div class="test">
        a. b. iはxxxxxxx
    </div>
    <div class="test">
        xxxxxxxxxxxxxxxxxxxxx（手）
    </div>
</div>
<div style="text-rendering: optimizelegibility">
    <div class="test">
        a. b. <span>i</span>はxxxxxxx
    </div>
    <div class="test">
        a. b. iはxxxxxxx
    </div>
    <div class="test">
        xxxxxxxxxxxxxxxxxxxxx（手）
    </div>
</div>