Fix w3c/w3c-website#105: Remove space between group name and group type, and make group type slightly less black

Author: jean-gui

assets-src/styles/sass/60-advanced-components/_collapsibles.scss

@@ -22,7 +22,7 @@
 			font-size: rem(15);
 			font-weight: normal;
 			line-height: calc(22.5 / 15);
-			margin-top: 1rem;
+			color: #333;
 			order: 2;
 			width: 100%;
 		}
@@ -65,4 +65,4 @@
 			display: none;
 		}
 	}
-}
+}