How to change the header menu color on Dawn theme?

[Boky]

Hi, I am currently using the Dawn theme and I want to change the header menu color. Just the menu section of the header, not the whole header itself.

I added this piece of code in Assets > Base.css, which made the menu the color I wanted. 

.header__inline-menu{
background:#ffffff;
}

Is there a way to expand the menu to be full paged? Any help would be much appreciated.

This is how it looks now.

This is how I would like it to look like.

[BSS-Commerce]

Hi @Boky 

Can you kindly share your store link (with the password, if any) with us? We will check it and suggest you a solution if possible.

[Boky]

Thanks for the fast response. I've sent you a PM.

[BSS-Commerce]

Hi @Boky 

We have checked on your store, but the header element is quite complicated. So we suggest you find a Shopify Expert or contact the theme provider to support you.