CSS

I'm setting up a new theme and I'm trying to add some CSS variables (example below) but every time I try, it seems that blot isn't parsing them and is basically ignoring that CSS. Are CSS variables supported? Example: :root { --text: #333; --bg: #fafafa; } body { color: var(--text); background: var(--bg); } Apologies if this question has been answered before, but the search bar isn't working for me. I just get a faded screen with no results.

Is there a way to change or manipulate stylesheets for minor changes that can affect the entire site? For example, just want to change the behavior of hyperlinks without manually recreating the existing pages.