Here is a pastel color palette designed for a calendar, featuring higher contrast colors for the heading cells:

json
{
  "palette_name": "Pastel Calendar with Contrast Headings",
  "colors": [
    {
      "name": "Pastel Pink",
      "hex_code": "
          
          #FFB3BA
       "
    },
    {
      "name": "Pastel Green",
      "hex_code": "
          
          #B9FBC0
       "
    },
    {
      "name": "Pastel Blue",
      "hex_code": "
          
          #A0D1E6
       "
    },
    {
      "name": "Pastel Yellow",
      "hex_code": "
          
          #FFEBB7
       "
    },
    {
      "name": "Deep Coral",
      "hex_code": "
          
          #FF6F61
       "
    },
    {
      "name": "Dark Slate Blue",
      "hex_code": "
          
          #483D8B
       "
    }
  ]
}

This palette combines soft pastel shades for the calendar cells with more vibrant colors for the heading cells to ensure they stand out clearly.

Would you like to adjust any specific colors or add more options to this palette?