fix: add spaced underscores and mobile dropdown for questions

- Change placeholder from "____" to "_ _ _ _" to show letter count
- Switch to dotted underlines for better visual distinction
- Add dropdown menu on mobile to prevent button overflow

src/clozeGameEngine.js

@@ -605,8 +605,8 @@ class ClozeGame {
           <input type="text" 
             class="cloze-input" 
             data-blank-index="${index}" 
-            placeholder="${'_'.repeat(Math.max(3, blank.originalWord.length))}"
-            style="width: ${Math.max(80, blank.originalWord.length * 12)}px;">
+            placeholder="${'_ '.repeat(Math.max(3, blank.originalWord.length)).trim()}"
+            style="width: ${Math.max(80, blank.originalWord.length * 16)}px;">
           <button id="${chatButtonId}" 
             class="chat-button text-blue-500 hover:text-blue-700 text-sm" 
             data-blank-index="${index}"

src/styles.css

@@ -255,7 +255,9 @@
 
   .cloze-input::placeholder {
     color: rgba(0, 0, 0, 0.4);
-    font-style: italic;
+    font-style: normal;
+    font-family: monospace;
+    letter-spacing: 0.1em;
   }
 
   .typewriter-button {