Title should have no background

This is especially important for dragging in edit mode when there is a gray background that we don't want to obstruct, but also in general if the accordion is styled with a background in a customization.

Author: reebalazs

packages/volto-accordion-block/src/theme/main.less

@@ -52,6 +52,7 @@
         padding: @itemVerticalPadding @itemHorizontalPadding;
         margin: 0;
       }
+
       // block chooser hover items don't have a bg color change, title block had a hover bg color
       .title {
         background: none;
@@ -110,7 +111,8 @@
 .block-editor-accordion {
   .accordion-item {
     border-top: 1px solid black;
-    clear: both; /* ensure floated images from content area don't spill over next accordion title */
+    /* ensure floated images from content area don't spill over next accordion title */
+    clear: both;
 
     &:last-child {
       border-bottom: 1px solid black;
@@ -126,6 +128,8 @@
     input {
       width: 100%;
       border: none;
+      /* No background, so the dragging works seamlessly */
+      background: none;
 
       &:focus {
         outline: none;