bottom-progress_style.css

:root {--accent: 255, 255, 255;}

.itemProgressBar {
  height: 5px;
  background: rgba(0,0,0,.5);
}

.playbackProgress>div, .itemProgressBarForeground {
    background-color: rgba(var(--accent), 0.75) !important;
}

.transcodingProgress>div {
    background-color: rgba(var(--accent), 0.35) !important;
}