theme.json

{
  "name": "Library Heading Colors",
  "author": "Matthias#8282",
  "manifest_version": 3,
  "target": "Tweak",
  "description": "This is a theme that allows you to re-color the library heading label and rule to colors that better fit your UI.",
  "inject": {
      "shared.css": ["SP", "MainMenu", "QuickAccess"]
  },
  "patches": {
    "Colors": {
        "type": "none",
        "values": {
            "_": {
                "shared.css": ["SP", "MainMenu", "QuickAccess"]
            }
        },
        "components": [
          {
              "name": "Label Color",
              "type": "color-picker",
              "on": "_",
              "default": "#ffffff99",
              "css_variable": "library-heading-recolor-label",
              "tabs": ["SP", "MainMenu", "QuickAccess"]
          },
          {
              "name": "Rule Color - Left",
              "type": "color-picker",
              "on": "_",
              "default": "#7e666633",
              "css_variable": "library-heading-recolor-rule-left",
              "tabs": ["SP", "MainMenu", "QuickAccess"]
          },
          {
              "name": "Rule Color - Right",
              "type": "color-picker",
              "on": "_",
              "default": "#ffffff00",
              "css_variable": "library-heading-recolor-rule-right",
              "tabs": ["SP", "MainMenu", "QuickAccess"]
          }
        ]
    }
  }
}