fix: Conditionally render error details to avoid layout gap

Co-authored-by: aider (gemini/gemini-2.5-pro) <aider@aider.chat>

webclient/src/Article.js

@@ -57,11 +57,13 @@ function Article({ cache }) {
 
 	return (
 		<div className='article-container'>
-			<details style={{marginBottom: '1rem', visibility: error ? 'visible' : 'hidden'}}>
+			{error &&
+				<details style={{marginBottom: '1rem'}}>
 					<summary>Connection error? Click to expand.</summary>
 					<p>{error}</p>
 					{story && <p>Loaded article from cache.</p>}
 				</details>
+			}
 			{story ?
 				<div className='article'>
 					<Helmet>

webclient/src/Feed.js

@@ -96,10 +96,12 @@ function Feed({ updateCache }) {
 				<title>QotNews</title>
 				<meta name="robots" content="index" />
 			</Helmet>
-			<details style={{marginBottom: '1rem', visibility: error ? 'visible' : 'hidden'}}>
+			{error &&
+				<details style={{marginBottom: '1rem'}}>
 					<summary>Connection error? Click to expand.</summary>
 					<p>{error}</p>
 				</details>
+			}
 			{stories ?
 				<div>
 					{stories.map(x =>