Fix footer + Add Posts preview + fix header + about + blog + index page

config/ColorMode.ts

@@ -0,0 +1,6 @@
+export default {
+  preference: 'system',
+  fallback: 'dark',
+  classPrefix: '',
+  classSuffix: '-mode',
+}

config/index.ts

@@ -1,4 +1,5 @@
 import Axios from './Axios'
 import Head from './Head'
+import ColorMode from './ColorMode'
 
-export { Axios, Head }
+export { Axios, Head, ColorMode }