The developer of mini.css addressed these concerns about IE support in a Hashnode story[0], raising some pretty compelling arguments about why it can't be done, not fully at least.
They say that they support older browsers and, from testing it lately, I haven't seen anything odd in IE 10 and 11, except the way images scale in the card media sections, which isn't really an issue in my eyes.
Maybe not today, but in a few months or a year, possibly. IE is dying and Edge is taking its place. Supporting IE just makes maintanance more difficult, doesn't it?
The semantics are reasonably outdated, but I wonder if part of this is due to certain things like using <section> might affect content placement and/or nesting (section classes are used only for cards so what if a card is inside a <section>?).
They state that older browsers and versions might be supported. I've tried this in IE 11 and it works like a charm, except for a couple of minor features. The diagram is the browsers that are "fully" supported.
Pen and paper, then quick mockup using a lightweight and easy framework like mini.css (https://chalarangelo.github.io/mini.css/index.html), then actual design. Sometimes I stick to mini.css, sometimes I use something heavier like Bootstrap or Semantic UI, but mini.css is pretty good for building simple mockups for me and sometimes I actually stick with it for some simpler designs.
Photoshop is just not my style, however I have friends that do use it and are very productive with it. It all comes down to preference.