rustdoc: use `.rustdoc` class instead of `body`

This didn't show up in our local tests, because the problem is actually
caused by docs.rs rewritten HTML (which relocates the classes that this
code looked for from the body tag to a child div).

Fixes #117290

1 files changed, 2 insertions, 2 deletions

diff --git a/src/librustdoc/html/static/js/main.js b/src/librustdoc/html/static/js/main.js
index 7c052606aba..615fb08c76f 100644
--- a/src/librustdoc/html/static/js/main.js
+++ b/src/librustdoc/html/static/js/main.js
@@ -54,7 +54,7 @@ function setMobileTopbar() {
     if (mobileTopbar) {
         const mobileTitle = document.createElement("h2");
         mobileTitle.className = "location";
-        if (hasClass(document.body, "crate")) {
+        if (hasClass(document.querySelector(".rustdoc"), "crate")) {
             mobileTitle.innerText = `Crate ${window.currentCrate}`;
         } else if (locationTitle) {
             mobileTitle.innerHTML = locationTitle.innerHTML;
@@ -485,7 +485,7 @@ function preLoadCss(cssUrl) {
                 return;
             }
 
-            const modpath = hasClass(document.body, "mod") ? "../" : "";
+            const modpath = hasClass(document.querySelector(".rustdoc"), "mod") ? "../" : "";
 
             const h3 = document.createElement("h3");
             h3.innerHTML = `<a href="${modpath}index.html#${id}">${longty}</a>`;