diff --git a/src/librustdoc/html/markdown.rs b/src/librustdoc/html/markdown.rs
index 98cc38a10d44d..a8d85fb6fb4ef 100644
--- a/src/librustdoc/html/markdown.rs
+++ b/src/librustdoc/html/markdown.rs
@@ -1574,7 +1574,6 @@ fn init_id_map() -> FxHashMap<Cow<'static, str>, usize> {
     map.insert("crate-search-div".into(), 1);
     // This is the list of IDs used in HTML generated in Rust (including the ones
     // used in tera template files).
-    map.insert("mainThemeStyle".into(), 1);
     map.insert("themeStyle".into(), 1);
     map.insert("settings-menu".into(), 1);
     map.insert("help-button".into(), 1);
diff --git a/src/librustdoc/html/templates/page.html b/src/librustdoc/html/templates/page.html
index 60ccfe4da4418..8cb43634377dc 100644
--- a/src/librustdoc/html/templates/page.html
+++ b/src/librustdoc/html/templates/page.html
@@ -15,8 +15,7 @@
     <link rel="stylesheet" {#+ #}
           href="{{static_root_path|safe}}{{files.normalize_css}}"> {# #}
     <link rel="stylesheet" {#+ #}
-          href="{{static_root_path|safe}}{{files.rustdoc_css}}" {#+ #}
-          id="mainThemeStyle"> {# #}
+          href="{{static_root_path|safe}}{{files.rustdoc_css}}"> {# #}
     {% if !layout.default_settings.is_empty() %}
     <script id="default-settings" {#+ #}
       {%~ for (k, v) in layout.default_settings ~%}