CSS: Split into modules

Don't place pure styling on top-level files (those that don't begin with underscore).
Instead, import them as individual files.

src/styles/components/_jumbotron.sass

@@ -0,0 +1,25 @@
+// Mainly overrides bootstrap jumbotron settings
+.jumbotron
+	background-size: cover
+	border-radius: 0
+	padding-top: 12em
+	padding-bottom: 12em
+
+	// Black-transparent gradient from left to right to better read the overlay text.
+	&.jumbotron-overlay
+		position: relative
+
+		&:after
+			background-image: linear-gradient(45deg, rgba(black, .5) 25%, transparent 50%)
+			bottom: 0
+			content: ''
+			left: 0
+			position: absolute
+			right: 0
+			top: 0
+
+		*
+			z-index: 1
+
+		h2, p
+			text-shadow: 1px 1px rgba(black, .2), 1px 1px 25px rgba(black, .5)