# How to Add Dark Mode to Any Website in 5 Minutes (with localStorage) Dark mode isn't just a trend anymore – it's an expected feature. Users want it for better readability and less eye strain. The good news? You can add it to any existing website in about 5 minutes with pure CSS and a few lines of JavaScript. No frameworks. No dependencies. Just copy, paste, and customize. What You'll Build A complete dark mode toggle that: ✅ Saves user preference in localStorage (persists across visits) ✅ Detects system theme automatically ✅ Lets users override system preference ✅ Works on any existing website Step 1: CSS Variables (The Foundation) CSS variables make theme switching effortless. Define your light theme as default, then override for dark mode.…