Bootstrap 4 customization (repaired in beta.2 version)

index.scss

// Bootstrap functions (required)

@import "vendor/bootstrap/functions";

// Customize

$white:  #ffddff;
$theme-colors: (
  primary: blue
);
// or: 
// @import "bootstrap-customize";

// Bootstrap Components (required)

@import "vendor/bootstrap/variables";
@import "vendor/bootstrap/mixins";

// Bootstrap Components (optional)

@import "vendor/bootstrap/print";
@import "vendor/bootstrap/reboot";
@import "vendor/bootstrap/type";
@import "vendor/bootstrap/images";
@import "vendor/bootstrap/code";