Fixes #65094: Style`hr` in markup content for hover

src/vs/editor/contrib/hover/hover.css

@@ -36,6 +36,14 @@
 	margin: 8px 0;
 }
 
+.monaco-editor-hover hr {
+	margin-top: 4px;
+	margin-bottom: -6px;
+	margin-left: -10px;
+	margin-right: -10px;
+	height: 1px;
+}
+
 .monaco-editor-hover p:first-child,
 .monaco-editor-hover ul:first-child {
 	margin-top: 0;

src/vs/editor/contrib/hover/hover.ts

@@ -284,6 +284,8 @@ registerThemingParticipant((theme, collector) => {
 	if (hoverBorder) {
 		collector.addRule(`.monaco-editor .monaco-editor-hover { border: 1px solid ${hoverBorder}; }`);
 		collector.addRule(`.monaco-editor .monaco-editor-hover .hover-row:not(:first-child):not(:empty) { border-top: 1px solid ${hoverBorder.transparent(0.5)}; }`);
+		collector.addRule(`.monaco-editor .monaco-editor-hover hr { border-top: 1px solid ${hoverBorder.transparent(0.5)}; }`);
+		collector.addRule(`.monaco-editor .monaco-editor-hover hr { border-bottom: 0px solid ${hoverBorder.transparent(0.5)}; }`);
 	}
 	const link = theme.getColor(textLinkForeground);
 	if (link) {