Add keywords inclusion tests

test/keywords/customize.css.txt

@@ -0,0 +1,32 @@
+https://fonts.googleapis.com/css?family=Nunito:400,700
+
+\* Bulma Base \*
+minireset.css
+html
+article
+aside
+
+.navbar
+.navbar.is-primary
+
+.button
+.button.is-primary
+.container
+.title
+
+\* Bulma Form \*
+.checkbox
+.radio
+.file
+.input
+.is-primary.input
+.textarea
+.is-primary.textarea
+.select
+.select.is-primary
+.label
+.help
+.field
+
+\* Bulma Utilities \*
+@keyframes spinAround