Design foundations

- Create a colour palette
- Create a sizing schema for paddings and fonts
- Implement basic form controls
- Create a theme demo page
- Apply the theme to the existing pages.

Still TODO is the final font selection.

snikket_web/scss/common.scss

@@ -0,0 +1,7 @@
+.a11y-only {
+	position: absolute;
+	width: 1px;
+	height: 1px;
+	overflow: hidden;
+	top: -100px;
+}