Colour

[maniks]

In which place in the elastic skin should be given this line <meta name = "theme-color" content = "# 0E1939"> to get the browser color on mobile devices?

[JohnDoh]

Editing core files is always tricky as your edits will not survive updates. You could extend the elastic skin, creating your own version with this tag in templates/includes/layout.html or you could use a plugin to inject the tag in, may be with the favicon object.