rustdoc: prevent method summary margin from being applied to docblocks

src/librustdoc/html/static/css/rustdoc.css

@@ -1980,8 +1980,8 @@ in storage.js
 	}
 }
 
-.method-toggle summary,
+.method-toggle > summary,
-.implementors-toggle summary,
+.implementors-toggle > summary,
 .impl,
 #implementors-list > .docblock,
 .impl-items > section,

src/test/rustdoc-gui/docblock-details.goml

@@ -21,3 +21,14 @@ assert-property: (".top-doc .docblock summary h4", {"offsetHeight": "33"})
 assert-css: (".top-doc .docblock summary h4", {"margin-top": "15px", "margin-bottom": "5px"})
 // So `33 + 15 + 5` == `53`
 assert-property: (".top-doc .docblock summary", {"offsetHeight": "53"})
+
+// We now check the `<summary>` on a method.
+assert-css: (
+    ".method-toggle .docblock summary h4",
+    {"border-bottom-width": "0px"},
+)
+// This allows to ensure that summary is on one line only!
+assert-property: (".method-toggle .docblock summary h4", {"offsetHeight": "30"})
+assert-css: (".method-toggle .docblock summary h4", {"margin-top": "15px", "margin-bottom": "5px"})
+// So `30 + 15 + 5` == `50`
+assert-property: (".method-toggle .docblock summary", {"offsetHeight": "50"})

src/test/rustdoc-gui/src/test_docs/lib.rs

@@ -317,6 +317,18 @@ pub mod details {
     /// <div>I'm the content of the details!</div>
     /// </details>
     pub struct Details;
+
+    impl Details {
+        /// We check the appearance of the `<details>`/`<summary>` in here.
+        ///
+        /// ## Hello
+        ///
+        /// <details>
+        /// <summary><h4>I'm a summary</h4></summary>
+        /// <div>I'm the content of the details!</div>
+        /// </details>
+        pub fn method() {}
+    }
 }
 
 pub mod doc_block_table {