Reader: remove width constraint on discover header (#98716)

client/components/scrollable-horizontal-navigation/styles.scss

@@ -1,16 +1,7 @@
-.is-section-reader .navigation-header.discover-stream-header {
-	margin: 0 auto;
-	max-width: 600px;
-	&.reader-dual-column {
-		max-width: 968px; // Max width of dual column reader stream.
-	}
-}
-
 .scrollable-horizontal-navigation {
 	position: relative;
 	margin: auto;
 	margin-bottom: -20px;
-	max-width: 600px; // Max width of single column reader stream.
 	overflow: hidden;
 	@media only screen and (max-width: 600px) {
 		padding: 0 24px;

client/reader/discover/discover-navigation.scss

@@ -1,7 +1,18 @@
-.is-section-reader .navigation-header.discover-stream-header {
-	margin: 0 auto;
-	max-width: 600px;
-	&.reader-dual-column {
-		max-width: 968px; // Max width of dual column reader stream.
+.is-section-reader {
+	.navigation-header.discover-stream-header {
+		margin: 0 auto;
+		padding: 0 0 24px 0;
+
+		@media only screen and ( max-width: 660px ) {
+			padding: 0 16px 24px;
+		}
+
+		&.reader-dual-column {
+			max-width: 968px; // Max width of dual column reader stream.
+		}
+	}
+	.discover-stream-navigation {
+		padding: 0;
+		margin-bottom: 0;
 	}
 }

client/reader/sidebar/style.scss

@@ -117,21 +117,6 @@ body.is-section-reader {
 			height: calc(100vh - var(--masterbar-height) - var(--content-padding-top) - var(--content-padding-bottom));
 		}
 	}
-
-	.is-discover-stream {
-		header.navigation-header.discover-stream-header {
-			padding: 0;
-			@media only screen and (max-width: 600px) {
-				padding: 0 24px;
-			}
-		}
-		@media only screen and (max-width: 660px) {
-			.discover-stream-navigation {
-				margin-left: 0;
-				margin-right: 0;
-			}
-		}
-	}
 }
 
 .is-section-reader {