public interface AppResources extends ClientBundle {
    public static final AppResources INSTANCE = GWT.create(AppResources.class);

    interface Style extends CssResource {
        String login();
    }

    @Source("css/style.gss")
    Style style();

    @Source("images/logo.png")
    ImageResource logo();
}

.login {
    width: 100%;
    height: 100%;
}

.login .panel-body {
    text-align: center;
}

.login .loginWrapper {
    display: flex;
    justify-content: center;
    align-items: center;
    width: 100%;
    height: 100%;
}

.login .input-group {
    padding-bottom: 10px;
    width: 300px;
}

.login .input-group-addon {
    width: 100px;
}

                     [ERROR] The following non-obfuscated class is present in a strict CssResource: panel-body. Fix by adding String accessor method(s) to the CssResource interface for obfuscated classes, or use an @external declaration for unobfuscated classes.
                     [ERROR] The following non-obfuscated class is present in a strict CssResource: input-group-addon. Fix by adding String accessor method(s) to the CssResource interface for obfuscated classes, or use an @external declaration for unobfuscated classes.
                     [ERROR] The following non-obfuscated class is present in a strict CssResource: input-group. Fix by adding String accessor method(s) to the CssResource interface for obfuscated classes, or use an @external declaration for unobfuscated classes.

   interface Style extends CssResource {
        String login();
    }