function content_scriptsCSS(file) {
    var link = document.createElement('link');
    link.href = chrome.runtime.getURL(file);
    link.rel = 'stylesheet';
    (document.head || document.documentElement).appendChild(link);
}

// 注入css
content_scriptsCSS('content_scripts.css');

function master_process(file) {
    var script = document.createElement('script');
    script.src = chrome.runtime.getURL(file);
    script.onload = function () {
        this.remove();
    };
    (document.head || document.documentElement).appendChild(script);

}
// 注入js
master_process('master_process.js');

// manifest.js
{
  "name": "addCssJs",
  "version": "1.0.0",
  "manifest_version": 3,
  "web_accessible_resources": [
    {
      "resources": [

        "content_scripts.css",
        "master_process.js"
      ],
      "matches": [
        "<all_urls>"
      ]
    }
  ]
}