Change the colour of the burger menu on the mobile - before opening.

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How do I change the colour of the burger menu on the mobile viewing. I need it to be a darker colour so you can see it on the background - it is currently the same colour as the background. 

I need it to remain the beige colour when against the red/brown background once the menu it's opened.

I have screenshot below and put a square where I am referencing. 

Thank you so much. 

Thank you 🙂