テキスト形式マークアップで HTML-style タグが使用可能になる。
Supported tags are:
<color="htmlcolor">colored text</color>, where "htmlcolor" is a html color string, like "#ff0000" or "red".
<b>bold text</b>
<i>italic text</i>
<size=20>sized text</size>
These are only supported for fonts set to use dynamic font rendering, except for the 'color' tag. Note that richText in Unity is not a full html implementation. Other tags are not supported.