​

​

function setup() {

  createCanvas(640, 480);

  board_w = 450;

  board_h = 450;

  space_w = (width-board_h)/2;

  space_h = (height-board_h)/2;

}

​

function draw() {

  background("black");

  noFill();

  stroke("white");

  rect(space_w, space_h, board_w, board_h);

}

​