diff --git a/features/steps/tui_app_coverage_steps.py b/features/steps/tui_app_coverage_steps.py
index fcf125b6c..9bfae6063 100644
--- a/features/steps/tui_app_coverage_steps.py
+++ b/features/steps/tui_app_coverage_steps.py
@@ -510,3 +510,13 @@ def step_alias_check(context):
     assert (
         context._tui_app_mod.CleverAgentsTuiApp.__name__ == "_TextualCleverAgentsTuiApp"
     )
+
+
+# ---------------------------------------------------------------------------
+# THEME class variable (issue #4742)
+# ---------------------------------------------------------------------------
+@then('the app class should have THEME set to "{theme}"')
+def step_theme_class_var(context, theme: str) -> None:
+    assert theme == context._tui_app.THEME, (
+        f"Expected THEME='{theme}', got '{context._tui_app.THEME}'"
+    )
diff --git a/features/tui_app_coverage.feature b/features/tui_app_coverage.feature
index 2392dca85..a610e42ea 100644
--- a/features/tui_app_coverage.feature
+++ b/features/tui_app_coverage.feature
@@ -196,3 +196,11 @@ Feature: TUI App Coverage
     And I call on_mount on the app
     And I submit "!true" to the app
     Then the conversation widget should contain "(empty output)"
+
+  # --- THEME class variable (issue #4742) ---
+
+  @tdd_issue @tdd_issue_4742
+  Scenario: The Textual TUI app has THEME set to dracula by default
+    Given a mock command router and persona state
+    When I instantiate the Textual TUI app
+    Then the app class should have THEME set to "dracula"
diff --git a/src/cleveragents/tui/app.py b/src/cleveragents/tui/app.py
index ca663fa8f..b1ff00785 100644
--- a/src/cleveragents/tui/app.py
+++ b/src/cleveragents/tui/app.py
@@ -89,6 +89,7 @@ if _TEXTUAL_AVAILABLE:
         """Main TUI app."""
 
         CSS_PATH: ClassVar[str] = "cleveragents.tcss"
+        THEME: ClassVar[str] = "dracula"
         BINDINGS: ClassVar[list[tuple[str, str, str]]] = [
             ("ctrl+q", "quit", "Quit"),
             ("f1", "help", "Help"),