学习记录卡片间距与单词列表保持一致

Co-Authored-By: Claude Opus 4.7 <noreply@anthropic.com>

LearnEnglish/LearnEnglish/Views/HistoryViewController.swift

@@ -6,7 +6,7 @@ final class HistoryViewController: UITableViewController {
 
     init() {
         sections = LearnedStore.shared.sectioned
-        super.init(style: .insetGrouped)
+        super.init(style: .plain)
     }
 
     @available(*, unavailable)
@@ -25,6 +25,7 @@ final class HistoryViewController: UITableViewController {
         tableView.register(WordCardCell.self, forCellReuseIdentifier: "cell")
         tableView.separatorStyle = .none
         tableView.backgroundColor = .systemBackground
+        tableView.contentInset.top = 8
         updateEmptyState()
 
         speechObserver = NotificationCenter.default.addObserver(