Add quotes around theme-color `content`. (#466)
Add quotes around theme-color `content`. (#466)

Probably missed this in the mime types PR. That moved the theme color
onto metadata, without surrounding it with quotes first.

Before:

    <meta name="theme-color" content=#fff>

After:

    <meta name="theme-color" content="#fff">
yoshuawuyts/bankai,choojs/bankai