safari(iOS) div will not fill height of td with height: 100%

<table>
    <tr>
        <td style="width:300px;height:300px;background-color:blue;"><div style="width:100%;height:100%;background-color:red;box-sizing:border-box;padding:10px;"></div></td>
    </tr>
</table>

only safari (iOS)

If I input 'padding:0px', div will fill height of td with height: 100%

but

if i input 'padding:10px', div will not fill height of td with height: 100%

Why?