Wrap logo in container to prevent layout reflow

Author: jakst

src/librustdoc/html/layout.rs

@@ -182,14 +182,16 @@ pub fn render<T: fmt::Display, S: fmt::Display>(
         let p = SlashChecker(&p);
         if layout.logo.is_empty() {
             format!("<a href='{path}index.html'>\
+                     <div class='logo-container'>\
                      <img src='{static_root_path}rust-logo{suffix}.png' \
-                          alt='logo' width='100'></a>",
+                          alt='logo' width='100'></div></a>",
                     path=p,
                     static_root_path=static_root_path,
                     suffix=page.resource_suffix)
         } else {
             format!("<a href='{}index.html'>\
-                     <img src='{}' alt='logo' width='100'></a>",
+                     <div class='logo-container'>\
+                     <img src='{}' alt='logo' width='100'></div></a>",
                     p,
                     layout.logo)
         }

src/librustdoc/html/static/rustdoc.css

@@ -182,6 +182,11 @@ nav.sub {
 	display: none !important;
 }
 
+.logo-container {
+	height: 0;
+	padding-bottom: 50%;
+}
+
 .sidebar img {
 	margin: 20px auto;
 	display: block;