Purr: overview tasks

[MaggieCabrera]

There are a few things that this theme needs to improve before launch. Feel free to open a PR for each of the items or open further issues if you find other problems:

• Templates have hardcoded colors, they should live in theme.json instead
• Same happens with spacing, let's figure out some global spacing values that we can use for the templates instead of hardcoded values
• The style.css needs changes. The author needs to be the wordpress.org user (let´s copy from blue note or stacks). The contributors that work on the theme will get a badge but the user right now can only be one, so all our themes have the same author. The WordPress versions need updating too
• After the design changes, we need to update the screenshot