Colorize the megamenu bar

Hallo everyone!

I have necessity to colorize themenu bar with a exact orange tone #fda72f.

I have try to insert into a /t3-assets/dev/templates.t3_bs3_blank.less.navbar.less.css file the color into:

.navbar-default {
background-color: #fda72f;
border-color: #e7e7e7;

but after some times, the setting is reset to default parameters

Why?

I think...this is not a default location to insert this parameters...the...who is the correct file to set this?

Thanks for the help.

Simone