fix

before.html

@@ -24,6 +24,8 @@
   elems.parentNode.insertBefore(info, elems);
 
   document.getElementById("target-select").addEventListener("change", (e) => {
-    alert(e.target.value);
+    // not very clever, just change the target at all.
+    // we could try to substitute the path or something better.
+    window.location.pathname = `${e.target.value}/std`;
   });
 </script>

build.sh

@@ -4,6 +4,8 @@ set -euxo pipefail
 
 root=$(realpath "$PWD")
 
+cp index.html "$root/www-root"
+
 # use a higher depth because bootstrap might be broken with depth 1?
 git clone --depth 50 https://github.com/rust-lang/rust.git
 cd rust
@@ -36,5 +38,3 @@ for target in "${targets[@]}"; do
 
     cp -rT "./build/$target/doc/" "$root/www-root/$target"
 done
-
-cp index.html "$root/www-root"