Write an HTML file with embedded CSS and JavaScript that, upon loading, generates a random maze using an algorithm that creates multiple paths (e.g. Kruskal or Prim). The user should be able to navigate the maze manually using the 'w', 'a', 's' and 'd' keys. Include a dropdown menu with options (breadth-first search, Depth-first search) and a button to solve the maze automatically using the selected algorithm. When the user clicks generate solution, make it visual (i.e. show the routes being explored) so the user can understand how the search works. The user should be able to reset the maze, and change the size of the maze.