rustdoc: make the hide setting apply in mobile

This makes the setting meaningful in all contexts: it hides the
sidebar on desktop, and hides the topbar on mobile.

Author: notriddle

src/librustdoc/html/static/css/rustdoc.css

@@ -1734,6 +1734,10 @@ in src-script.js
 		top: 0;
 	}
 
+	.hide-sidebar .mobile-topbar {
+		display: none;
+	}
+
 	.sidebar-menu-toggle {
 		width: 45px;
 		/* Rare exception to specifying font sizes in rem. Since this is acting

src/librustdoc/html/static/js/settings.js

@@ -194,7 +194,7 @@
                 "default": false,
             },
             {
-                "name": "Hide navigation sidebar",
+                "name": "Hide persistent navigation bar",
                 "js_name": "hide-sidebar",
                 "default": false,
             },

tests/rustdoc-gui/hide-mobile-topbar.goml

@@ -0,0 +1,20 @@
+// Checks sidebar resizing stays synced with the setting
+go-to: "file://" + |DOC_PATH| + "/test_docs/index.html"
+set-window-size: (400, 600)
+
+// Verify that the "hide" option is unchecked
+click: "#settings-menu"
+wait-for: "#settings"
+assert-css: ("#settings", {"display": "block"})
+assert-property: ("#hide-sidebar", {"checked": "false"})
+assert-css: (".mobile-topbar", {"display": "flex"})
+
+// Toggle it
+click: "#hide-sidebar"
+assert-property: ("#hide-sidebar", {"checked": "true"})
+assert-css: (".mobile-topbar", {"display": "none"})
+
+// Toggle it again
+click: "#hide-sidebar"
+assert-property: ("#hide-sidebar", {"checked": "false"})
+assert-css: (".mobile-topbar", {"display": "flex"})