manifest.json

{
    "manifest_version": 3,
    "name": "Monochrome Theme for Gmail",
    "version": "1.0",
    "description": "A modern and minimalistic Monochrome theme for Gmail.",
    "author": "jessedi0n",
    "permissions": [
        "activeTab"
    ],
    "icons": {
        "16": "icons/gmail-mono.png",
        "48": "icons/gmail-mono.png",
        "128": "icons/gmail-mono.png"
    },
    "content_scripts": [
        {
            "matches": [
                "https://mail.google.com/*"
            ],
            "css": [
                "styles.css"
            ],
            "js": [
                "content.js"
            ],
            "run_at": "document_end"
        }
    ],
    "web_accessible_resources": [
        {
            "resources": [
                "icons/*"
            ],
            "matches": [
                "<all_urls>"
            ],
            "use_dynamic_url": true
        }
    ]
}