this style helps me get along with the recent slack redesign

better-slack.css

@-moz-document url-prefix("https://app.slack.com") {
    .p-top_nav {
        background: transparent !important;
        box-shadow: none;
        pointer-events: none;
    }
    .p-workspace {
        margin-top:-38px;   
    }
    .p-top_nav__sidebar {
        flex: 2;
    }
    .p-top_nav__search {
        background: transparent;
        color: #333;
        pointer-events: all;
        flex: 1;
        box-shadow: inset 0 0 0 1px #ccc;
    }
    .p-top_nav__search:hover {
        background: white;
        box-shadow: inset 0 0 0 1px rgb(138,176,189);
    }
    .p-top_nav__right {
        justify-content: flex-start;
        padding-left:3px;
        flex: 2;
    }
    .p-top_nav__button {
        color: #777;
        pointer-events: all;
    }
    .p-top_nav__sidebar .p-top_nav__history_menu {
        margin-right:-30px;
        pointer-events: all;
    }
}