How to change the play button on audio block?

Site URL: https://www.lassiettestantoine.com

Hello, 

I am struggling to change the colour of the play button on my audio block to a light blue ? 
And if in addition someone knows how to alter the padding of the audio block ? <-- the background colour is too big compare to the text. 

Thank you so much for your help 

Add to Home > Design > Custom CSS

.play-button {
    border-left-color: green !important;
}