concarneau: make second-level headers semi-bold (#30597)

static/concarneau/_custom.scss

@@ -423,6 +423,10 @@ body {
                         text-transform: uppercase;
                     }
 
+					.cell h2 {
+						@extend %title;
+					}
+
                     .cell h3,
                     .cell h4,
                     .cell h5,

static/concarneau/_vars.scss

@@ -28,6 +28,8 @@ $border-radius: 0px;
 
 $title-background: white;
 $title-color: $secondary-color;
+$title-font-family: OpenSans-SemiBold,Arial,Verdana,Helvetica,sans-serif;
+$title-font-size: 23px;
 
 $footer-background: transparent;
 $footer-color: white;