fix: ui bugs

src/components/DigitsInput.tsx

@@ -57,10 +57,20 @@ const DigitInput: React.FC<DigitInputProps> = ({
     event: KeyboardEvent<HTMLDivElement>,
     index: number,
   ) => {
-    if (event.key === 'Backspace' && code[index]) {
+    if (event.key === 'Backspace') {
       event.preventDefault();
-      handleChange('', index);
-      if (index > 0) inputRefs.current[index - 1]?.focus();
+
+      if (code[index]) {
+        // We clear the current value.
+        handleChange('', index);
+      } else if (index > 0) {
+        // We move focus to the previous input and SELECT its content.
+        const prevInput = inputRefs.current[index - 1];
+        if (prevInput) {
+          prevInput.focus();
+          prevInput.select();
+        }
+      }
     }
   };