Improve JSX intrinsic element types

Uses `JSX.IntrinsicElements['span']` as base JSX intrinsic element type
if it exists (e.g. `@types/react` installed), and a generic record
otherwise. Explicitly add "class" for React JSX, because "className" is
not supported for custom elements.

Author: ingmarh

src/index.ts

@@ -1,16 +1,17 @@
 import { ScrollShadowElement } from './ScrollShadowElement.js'
 
+type IntrinsicBase = JSX.IntrinsicElements extends { span: infer SpanElement }
+	? SpanElement
+	: Record<string, unknown>
+
 declare global {
 	interface HTMLElementTagNameMap {
 		'scroll-shadow': ScrollShadowElement
 	}
 
 	namespace JSX {
 		interface IntrinsicElements {
-			'scroll-shadow': {
-				// eslint-disable-next-line @typescript-eslint/no-explicit-any
-				[prop: string]: any
-			}
+			'scroll-shadow': IntrinsicBase & { class?: string }
 		}
 	}
 }