As mentioned in #235 (comment) it would be nice to have a way to set color modes via a css class.
colors: {
    default: {
        text: '#000',
        background: '#fff',
        primary: '#07c',
        secondary: '#05a',
        accent: '#609',
        muted: '#f6f6f6',
    },
    dark: { ... },
    extraDark: { ... },
    pink: { ... }
},<body>
<body class="dark">
<body class="pink">
<body class="extra-dark">