Make the hidden attribute win over display rules

.drop-overlay sets display: flex, which beats the UA's [hidden] rule, so
the "Drop to analyse" overlay covered the page permanently and hid the
status line. A global [hidden] { display: none !important } fixes it and
any other element that pairs `hidden` with a display class.

Co-Authored-By: Claude Opus 5 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_015UXA39Sh9coAx4FhRkd8R2

master_core.py

@@ -7,7 +7,13 @@ import numpy as np
 from mutagen.mp3 import MP3
 from mutagen.easyid3 import EasyID3
 
-from font_manager import safe_title
+
+def safe_title(title):
+  # Deliberately not font_manager.safe_title: that module imports PyQt5 at load
+  # time, and master_core is on the Qt-free web path (the `web` extra has no Qt).
+  if not title:
+    return title
+  return title.encode('utf-8', errors='replace').decode('utf-8')
 
 
 def _try_mp3_tags(file_path):

static/app.css

@@ -20,6 +20,11 @@
 
 * { box-sizing: border-box; }
 
+/* The UA's [hidden] { display: none } loses to any class that sets display
+   (e.g. .drop-overlay's flex), which left the overlay permanently covering the
+   page. Make the attribute win everywhere. */
+[hidden] { display: none !important; }
+
 html, body {
   margin: 0;
   height: 100%;