I haven't heard of any of those except BEM. Which you are using at Shopify, you just might not know it's called that. And it's not really a tech, it's just the style of naming css classes, "block element modifier" like on your home page: "marketing-form__fallback-cta" - marketing-form is the block, "__fallback-cta" is the element (only has meaning within the block), and if you had something like "--purplesmoke" that would be the modifier. Super simple, link here: http://getbem.com/naming/