2018-12-29 Firefox extensions I can not live without

My current list of Firefox extensions on my Mac is as follows:

Turn off auto-playing of videos, and turn on parsing of userChrome in about:config:

And finally to fit things in perfectly, create a userChrome.css to move the tabbar close button to the left:

    .tabbrowser-tab:not([pinned]) .tab-close-button {
        -moz-box-ordinal-group: 0 !important;
        -moz-margin-start:-4px !important;
        -moz-margin-end:4px !important;