Fix error icon styling and tooltip functionality

- Removed error icon from parallel field (optional field with default value)
- Added black background to error icons (#000000)
- Added hover effect to error icons (changes to blue on hover)
- Added proper tooltip popup for error icons (same as ? tooltip)
- Removed inline styles from HTML, moved to CSS

css/styles.css

@@ -309,20 +309,30 @@ html[lang="en"] .tooltip-icon:hover::after {
 
 .error-icon {
   display: none;
-  font-size: 14px;
+  width: 16px;
+  height: 16px;
+  background-color: #000000;
+  color: #FFFFFF;
+  text-align: center;
+  line-height: 16px;
+  font-family: 'Courier New', monospace;
+  font-size: 12px;
   font-weight: bold;
-  line-height: 1;
   cursor: help;
   user-select: none;
 }
 
+.error-icon:hover {
+  background-color: #0000FF;
+}
+
 .error-icon:hover::after {
   content: attr(data-tooltip);
   position: absolute;
   bottom: 100%;
   left: 50%;
   transform: translateX(-50%);
-  background-color: #FF0000;
+  background-color: #000000;
   color: #FFFFFF;
   padding: 8px 12px;
   font-size: 11px;