Minimal The Grid styling

[jonnor]

Currently we use a stock aglio template.

Should at least:

• Tweak color, typography to match The Grid brand
• Add The Grid logo, links out to https://thegrid.io

[jonnor]

We have our own Aglio template now, extending the default 'Slate'. It is at https://github.com/the-grid/apidocs/tree/master/templates/aglio

Just needs someone design minded to go and tweak the CSS appropriately... @narrowdesign ?