_variables.less

[ElasticUser]

"/* Here you can re-define any of variables from variables.less, colors.less and fontawesome.less */"

I changed (#fff) to (#fff000) in 3 (_variables.less) places as a test, and cleared out the cache, but I don't see the (fff000) color changes.  The re-define sentence is very easy for me to catch on to, but I appear to be missing something.   

// Layout elements
@color-layout-border:               @color-black-shade-border;
@color-layout-header:               @color-font;
@color-layout-sidebar-background:   #FFF000;
@color-layout-list-background:      #FFF000;
@color-layout-content-background:   #FFF000;
@color-layout-header-background:    #f4f4f4;
@color-layout-footer-background:    #fff;

[SKaero]

.less files need to be complied into actual css files.

[ElasticUser]

So I should change (_variables.less) to (_variables.css)?   

[SKaero]

No that wont work since less isn't valid css. There are directions on how to compile the less files in the README in the elastic skin folder https://github.com/roundcube/roundcubemail/blob/master/skins/elastic/README.md

[ElasticUser]

Otay