github-notification-fixer.user.css

/** remove new shitty header, bring back old style notifications **/
.notifications-list-item .notification-list-item-link .d-flex.flex-column.flex-auto .d-flex {
    display: none !important;
}
.notifications-list-item .Label {
    display: none !important
}
.notification-list-item-actions {
    display: flex !important;
}
.js-notification-action button {
    background: none;
    border: none;
}
relative-time {
    display: block !important;
    color: #6a737d !important;
    position: absolute;
    left: 660px;
}

.Box-header {
    max-height: 36px !important;
}
.Box-header h6 {
    font-size: 15px !important;
}


/** remove "mark as done" text from buttons **/
button[title="Mark as done"] {
    text-align: left !important;
    text-indent: -9999px;
    width: 25px !important;
    height: 25px !important;
}
button[title="Mark as done"] span {
    text-indent: 9994px !important;
}


/** hide clutter and tidy up list **/
nav.notification-navigation,
.js-notification-sidebar-repositories,
.js-notification-sidebar-filters {
    display: none !important;
}

.js-check-all-container {
    max-width: 60% !important;
    margin: 0 auto;
}

.js-notifications-group {
    margin-top: 30px !important;
}

.notification-list-item-unread-indicator,
.js-notification-bulk-action-check-item {
    /*display: none !important;*/
}

button[title="Save"] {
    display: none !important;
}