I saw a question in Facebook group regarding active menu styling.

Is there a way to make the menu item you have selected be bolder once selected?

To let visitors know what page they currently visited, in Divi Menu Module, you can have different text color for active link.

Active Link Color in Divi

Menu Settings

To add more styling for active menu, you can use selector li.current-menu-item a.

For the above question, below can be added as Custom CSS.

#menu-main-menu li.current-menu-item a {
  font-weight: bold !important;
}