control image sizing through Kindly and SCSS

[daslu]

discussion: https://clojurians.zulipchat.com/#narrow/stream/422115-clay-dev/topic/images/near/426488651

[genmeblog]

I would enhance this to all hardcoded styles in Clay. I mean I propose to avoid any styles in the code at all. This applies to separator (https://github.com/scicloj/clay/blob/main/src/scicloj/clay/v2/item.clj#L82), embedded charts (https://github.com/scicloj/clay/blob/main/src/scicloj/clay/v2/item.clj#L119).