Here is a color palette featuring 12 lighter colors that can be effectively used as headers in Excel:

json
{
  "palette_name": "Light Header Colors",
  "colors": [
    {
      "name": "Light Blue",
      "hex_code": "
          
          #ADD8E6
       "
    },
    {
      "name": "Light Green",
      "hex_code": "
          
          #90EE90
       "
    },
    {
      "name": "Light Coral",
      "hex_code": "
          
          #F08080
       "
    },
    {
      "name": "Light Yellow",
      "hex_code": "
          
          #FFFFE0
       "
    },
    {
      "name": "Lavender",
      "hex_code": "
          
          #E6E6FA
       "
    },
    {
      "name": "Peach Puff",
      "hex_code": "
          
          #FFDAB9
       "
    },
    {
      "name": "Misty Rose",
      "hex_code": "
          
          #FFE4E1
       "
    },
    {
      "name": "Light Goldenrod Yellow",
      "hex_code": "
          
          #FAFAD2
       "
    },
    {
      "name": "Honeydew",
      "hex_code": "
          
          #F0FFF0
       "
    },
    {
      "name": "Lavender Blush",
      "hex_code": "
          
          #FFF0F5
       "
    },
    {
      "name": "Light Sea Green",
      "hex_code": "
          
          #20B2AA
       "
    },
    {
      "name": "Pale Turquoise",
      "hex_code": "
          
          #AFEEEE
       "
    }
  ]
}

This palette includes soft and light colors that can help enhance the visual appeal of headers in your Excel sheets. Would you like more information on how to apply these colors in Excel or any other assistance?