Check out example codes for "css customize audio player". It will help you in understanding the concepts better.

Code Example 1

audio {
    filter: sepia(20%) saturate(70%) grayscale(1) contrast(99%) invert(12%);
    width: 200px;
    height: 25px;
}

/*or*/

audio::-webkit-media-controls-panel

audio::-webkit-media-controls-mute-button

audio::-webkit-media-controls-play-button

audio::-webkit-media-controls-timeline-container

audio::-webkit-media-controls-current-time-display

audio::-webkit-media-controls-time-remaining-display

audio::-webkit-media-controls-timeline

audio::-webkit-media-controls-volume-slider-container

audio::-webkit-media-controls-volume-slider

audio::-webkit-media-controls-seek-back-button

audio::-webkit-media-controls-seek-forward-button

audio::-webkit-media-controls-fullscreen-button

audio::-webkit-media-controls-rewind-button

audio::-webkit-media-controls-return-to-realtime-button

audio::-webkit-media-controls-toggle-closed-captions-button

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