add tailwind theme

pages/_meta.json

@@ -3,5 +3,6 @@
   "cli": "CLI",
   "git": "Git",
   "dev_ops": "Dev Ops",
-  "latex": "LaTeX"
+  "latex": "LaTeX",
+  "web_dev": "Web Development"
 }

pages/web_dev/tailwind_theme.md

@@ -0,0 +1,82 @@
+---
+tags:
+  - tailwind
+  - theme
+  - css variables
+  - dark mode
+---
+
+# Tailwind themes with CSS Variables
+
+There are many tailwind theme plugins, tried few and landed on`tailwindcss-themer`.
+
+## Setup
+
+Two files are required:
+
+1. `pnpm i -D tailwindcss-themer`
+1. `tailwind.config.js`
+1. `app.postcss`
+
+> Technically, we don't need to use CSS variables, but I like to, as I can export them automatically from Figma, or whatever design tool. Without CSS Variables, you could just define the colors in `tailwind.config.js` without touching css files.
+
+```js
+// tailwind.config.js
+
+const themer = require('tailwindcss-themer')
+
+/** @type {import('tailwindcss').Config}*/
+const config = {
+  theme: {
+    // ...
+  },
+
+  plugins: [
+    themer({
+      defaultTheme: {
+        extend: {
+          colors: {
+            primary: 'var(--colors-cyan-500)',
+            secondary: 'var(--colors-yellow-500)',
+            surface: 'var(--colors-gray-100)',
+            text: 'var(--colors-gray-900)',
+          },
+        },
+      },
+      themes: [
+        {
+          name: 'darker',
+          mediaQuery: '@media (prefers-color-scheme: dark)',
+          extend: {
+            colors: {
+              primary: 'var(--colors-cyan-700)',
+              secondary: 'var(--colors-yellow-500)',
+              surface: 'var(--colors-gray-900)',
+              text: 'var(--colors-gray-100)',
+            },
+          },
+        },
+      ],
+    }),
+  ],
+}
+
+module.exports = config
+```
+
+```css
+/* app.postcss */
+
+@tailwind base;
+@tailwind components;
+@tailwind utilities;
+
+:root {
+  /* colors */
+  --colors-cyan-500: rgb(164, 189, 245);
+  --colors-cyan-700: #0d398c;
+  --colors-gray-100: rgb(255, 255, 255);
+  --colors-gray-900: rgb(1, 1, 1);
+  --colors-yellow-500: rgb(233, 246, 82);
+}
+```