<script src="https://cdnjs.cloudflare.com/ajax/libs/p5.js/1.3.1/p5.min.js"></script>

body {
  margin: 0;
  overflow: hidden;
}

function setup() {
  createCanvas(windowWidth, windowHeight)
  background('#fbf8f3')
}

function draw() {
  if (mouseIsPressed) {
    fountainPen()
  }
}

function fountainPen() {
  // set the color and brush style
	stroke(0, 0, 0, 255)
	strokeWeight(1)
	const width = 5

  // draw a slanted line 
  line(mouseX - width, mouseY - width, mouseX + width, mouseY + width)
}