Improve styling of the info panel

[BurkusCat]

When you hover over an operator or relationship, an info panel shows. The HTML and CSS structure and code for all of this is a bit messy. Changes that would be good:

• Links don't make sense for any of the elements
• Remove underlines from text
• Restructure the code and use better CSS (instead of the HTML strong tag etc.)
• Restructure the info panel so that schema.org or https://developers.google.com/search/docs/advanced/structured-data can be used
  • "Character" is the structured data type we want
• Background color behind the name of the operator should use the operator icon's color
• The color should be darkened so that the white text is more legible

[BurkusCat]

Current info panel: