The easiest way to write conditional CSS and/or JavaScript based on device operating system (iOS, Android, Blackberry, Windows, Firefox OS, MeeGo, AppleTV, etc), orientation (Portrait vs. Landscape), and type (Tablet vs. Mobile).
Nuxt is a free and open-source framework with an intuitive and extendable way to create type-safe, performant and production-grade full-stack web applications and websites with Vue.js.
SVG sprites & stacks galore — A low-level Node.js module that takes a bunch of SVG files, optimizes them and bakes them into SVG sprites of several types along with suitable stylesheet resources (e.g. CSS, Sass, LESS, Stylus, etc.)