Background/foreground color problem on Emacs on Windows

I'm using Emacs on Windows.

In my .emacs file, I changed the background and foreground colors.

When I opened Emacs, the color changes occurred.

But when I opened a new frame using C-x 5 2, the color changes did not开发者_如何学C occur.

Why?

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This is how I do it:

(setq default-frame-alist
       `((background-color . "darkslateblue")
         (foreground-color . "lightcyan")))