Switch to Hugo.

No more Ruby dependency and most important more than 10 times less build time (at least on Windows)!

site/data/grays.yml

@@ -0,0 +1,18 @@
+- name: 100
+  hex: "#f8f9fa"
+- name: 200
+  hex: "#e9ecef"
+- name: 300
+  hex: "#dee2e6"
+- name: 400
+  hex: "#ced4da"
+- name: 500
+  hex: "#adb5bd"
+- name: 600
+  hex: "#868e96"
+- name: 700
+  hex: "#495057"
+- name: 800
+  hex: "#343a40"
+- name: 900
+  hex: "#212529"