Here’s a refined color palette featuring black violet for the background and accent blue for the buttons:

json
{
  "palette_name": "Cinema Web Theme with Black Violet",
  "colors": [
    {
      "name": "Black Violet",
      "hex_code": "
          
          #2E1A47
       "
    },
    {
      "name": "Accent Blue",
      "hex_code": "
          
          #007BFF
       "
    },
    {
      "name": "Dark Blue",
      "hex_code": "
          
          #1A1A6E
       "
    },
    {
      "name": "Light Blue",
      "hex_code": "
          
          #A3C1E0
       "
    },
    {
      "name": "Soft Gray",
      "hex_code": "
          
          #F0F0F0
       "
    }
  ]
}

This palette utilizes black violet as a nearly black background, providing a sleek and sophisticated base, while the accent blue serves as a vibrant contrast for buttons, ensuring they stand out effectively.

Would you like to explore more variations or perhaps different design elements for your project?