Styling the button that opens the form popup without affecting other buttons

Site URL: https://jeffpow.com

Hi everyone, 

Need your help.

Attached are the button styling I want (dark).

I've input these CSS code as follows:

button {
    font-size: 21px !important;
      font-weight: 500 !important;
    padding-top: 34px !important;;
    padding-bottom: 34px !important;;
    padding-left: 80px !important;;
    padding-right: 80px !important;;
    border-radius: 0px !important;;
    color: #ffffff !important;
    background: #36150d !important;  
}

However, it affected other portions too.

As attached.

Not sure why. Thanks.

try change button to button.lightbox-handle

If it doesn't work, can you share link to page where you use button? We can check easier