feat: ✨ auto switch dark-light themes

ref: #1

README.md

@@ -12,6 +12,10 @@
 
 ![light theme](figs/light.png)
 
+## `auto`
+
+Switches between `dark` and `light` automatically based on the user's system preference.
+
 ## Usage
 
 1. Clone this repo
@@ -20,7 +24,7 @@
 
 ```ini
 [ui]
-THEMES=...,dark,light
+THEMES=...,dark,light,auto
 DEFAULT_THEME=dark # optional
 ```
 

dist/public/assets/css/theme-auto.css

@@ -0,0 +1 @@
+@import "./theme-light.css"(prefers-color-scheme:light);@import "./theme-dark.css"(prefers-color-scheme:dark);

src/themes/scss/auto.scss

@@ -0,0 +1,2 @@
+@import "./theme-light.css" (prefers-color-scheme: light);
+@import "./theme-dark.css" (prefers-color-scheme: dark);