为什么会出现白框？

Question

循环输出的第一个框是一个带有黑色轮廓的白色框。我不明白它来自哪里...... https://editor.p5js.org/matranson/present/6fNelJM8_

function setup() {

    colorMode(HSB,360,100,100);

    createCanvas(400, 400);

    var boxh = height / 10;

    var boxw = width;

    for(var i = 0; i < 10; i++) {

    var h = lerp(64, 22, i / 9);

    var s = lerp(86, 90, i / 9);

    var l = lerp(96, 56, i / 9);

    rect(0, i * boxh, boxw, boxh);

    fill(h,s,l);   

    stroke(0,0,100);

    }

    

}

function draw() {

}

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