[karabiner] Volume keys to Volume keys with Ctrl + Option

fine-volume-keys.json

{
    "description": "Volume keys to Volume keys with Ctrl + Option",
    "manipulators": [
        {
            "from": { "key_code": "f11" },
            "to": [
                {
                    "key_code": "volume_decrement",
                    "modifiers": ["left_shift", "left_option"]
                }
            ],
            "type": "basic"
        },
        {
            "from": { "consumer_key_code": "volume_decrement" },
            "to": [
                {
                    "key_code": "volume_decrement",
                    "modifiers": ["left_shift", "left_option"]
                }
            ],
            "type": "basic"
        },
        {
            "from": { "consumer_key_code": "volume_increment" },
            "to": [
                {
                    "key_code": "volume_increment",
                    "modifiers": ["left_shift", "left_option"]
                }
            ],
            "type": "basic"
        },
        {
            "from": { "key_code": "f12" },
            "to": [
                {
                    "key_code": "volume_increment",
                    "modifiers": ["left_shift", "left_option"]
                }
            ],
            "type": "basic"
        }
    ]
}