jupyter_notebook/static/notebook/less/savewidget.less

span.save_widget {
    margin-top: 6px;
    
    span.filename {
        height: 1em;
        line-height: 1em;
        padding: 3px;
        margin-left: @padding-large-horizontal;
        border: none;
        font-size: 146.5%;
        &:hover{
            // ensure body is lighter on dark palette, 
            // and vice versa
            background-color:contrast(@body-bg, lighten(@body-bg,30%), darken(@body-bg,10%));
        }
        .corner-all;
    }
}

span.checkpoint_status, span.autosave_status {
    font-size: small;
}

@media (max-width: @screen-xs-max) {
    span.save_widget {
        font-size: small;
    }
    span.checkpoint_status, span.autosave_status {
      display: none;
    }
}

@media (min-width: @screen-sm-min) and (max-width: @screen-sm-max) {
    span.checkpoint_status {
        display: none;
    }
    span.autosave_status {
        font-size: x-small;
    }
}