This HTML5 Audio Player is ideal to add background music to your website because it will ensure a continuous and smooth playback across your entire website. You can customize this html5 audio player by changing the color for: player background, volume slider, timer, buffer, seekbar, song title, playlist background, playlist font and playlist item line separator.

Demo: https://codecanyon.net/item/sticky-html5-music-player-wordpress-plugin/7796273