Simplify and unify rustdoc sidebar styles

This switches to just use size, weight, and spacing to distinguish
headings in the sidebar. We no longer use boxes, horizontal bars, or
centering to distinguish headings. This makes it much easier to
understand the hierarchy of headings, and reduces visual noise.

I also refactored how the mobile topbar works. Previously, we tried to
shift around elements from the sidebar to make the topbar. Now, the
topbar gets its own elements, which can be styled on their own. This
makes styling and reasoning about those elements simpler.

Because the heading font sizes are bigger, increase the sidebar width
slightly.

As a very minor change, removed version from the "All types" page. It's
now only on the crate page.

src/librustdoc/html/render/context.rs

@@ -554,16 +554,8 @@ impl<'tcx> FormatRenderer<'tcx> for Context<'tcx> {
             extra_scripts: &[],
             static_extra_scripts: &[],
         };
-        let sidebar = if let Some(ref version) = self.shared.cache.crate_version {
-            format!(
-                "<h2 class=\"location\">Crate {}</h2>\
-                     <div class=\"block version\">\
-                         <p>Version {}</p>\
-                     </div>\
-                     <a id=\"all-types\" href=\"index.html\"><p>Back to index</p></a>",
-                crate_name,
-                Escape(version),
-            )
+        let sidebar = if self.shared.cache.crate_version.is_some() {
+            format!("<h2 class=\"location\">Crate {}</h2>", crate_name)
         } else {
             String::new()
         };

src/librustdoc/html/render/mod.rs

@@ -1744,13 +1744,6 @@ fn print_sidebar(cx: &Context<'_>, it: &clean::Item, buffer: &mut Buffer) {
             buffer,
             "<h2 class=\"location\"><a href=\"#\">{}{}</a></h2>",
             match *it.kind {
-                clean::StructItem(..) => "Struct ",
-                clean::TraitItem(..) => "Trait ",
-                clean::PrimitiveItem(..) => "Primitive Type ",
-                clean::UnionItem(..) => "Union ",
-                clean::EnumItem(..) => "Enum ",
-                clean::TypedefItem(..) => "Type Definition ",
-                clean::ForeignTypeItem => "Foreign Type ",
                 clean::ModuleItem(..) =>
                     if it.is_crate() {
                         "Crate "
@@ -1763,26 +1756,14 @@ fn print_sidebar(cx: &Context<'_>, it: &clean::Item, buffer: &mut Buffer) {
         );
     }
 
+    buffer.write_str("<div class=\"sidebar-elems\">");
     if it.is_crate() {
+        write!(buffer, "<div class=\"block\"><ul>");
         if let Some(ref version) = cx.cache().crate_version {
-            write!(
-                buffer,
-                "<div class=\"block version\">\
-                     <div class=\"narrow-helper\"></div>\
-                     <p>Version {}</p>\
-                 </div>",
-                Escape(version),
-            );
+            write!(buffer, "<li class=\"version\">Version {}</li>", Escape(version));
         }
-    }
-
-    buffer.write_str("<div class=\"sidebar-elems\">");
-    if it.is_crate() {
-        write!(
-            buffer,
-            "<a id=\"all-types\" href=\"all.html\"><p>See all {}'s items</p></a>",
-            it.name.as_ref().expect("crates always have a name"),
-        );
+        write!(buffer, "<li><a id=\"all-types\" href=\"all.html\">All Items</a></li>");
+        buffer.write_str("</div></ul>");
     }
 
     match *it.kind {
@@ -1806,7 +1787,7 @@ fn print_sidebar(cx: &Context<'_>, it: &clean::Item, buffer: &mut Buffer) {
     // to navigate the documentation (though slightly inefficiently).
 
     if !it.is_mod() {
-        buffer.write_str("<h2 class=\"location\">Other items in<br>");
+        buffer.write_str("<h2 class=\"location\">In ");
         for (i, name) in cx.current.iter().take(parentlen).enumerate() {
             if i > 0 {
                 buffer.write_str("::<wbr>");