More layout fiddling and error page

src-web/components/Heading.tsx

@@ -0,0 +1,12 @@
+import classnames from 'classnames';
+import type { HTMLAttributes } from 'react';
+
+type Props = HTMLAttributes<HTMLHeadingElement>;
+
+export function Heading({ className, children, ...props }: Props) {
+  return (
+    <h1 className={classnames(className, 'text-2xl font-semibold text-gray-900 mb-3')} {...props}>
+      {children}
+    </h1>
+  );
+}