changer police et intégrer dans le fond de la page

Bonjour,
je suis en train de faire un site sous OpenElement. J'ai trouvé une animation sympa en html+css+js
je veux la modifier mais je n'ai pas les connaissances requises (ni même le minimum syndical).

<canvas></canvas>

body {
    width: 100vw;
    height: 100vh;

    margin: 0;
    padding: 0;
}

    opacity: 1;
    visibility: visible;

    transition: all .5s;
}

h3, h5 {
    padding: 10px 30px 10px 30px;
    box-sizing: border-box;

    background: rgba(255, 255, 255, 1);
    box-shadow: 0 0 5px 0 black;

    font-family: 'Open Sans';
    font-weight: 300;
    text-align: center;
    letter-spacing: 3px;
}

span#close {
    position: absolute;
    top: -15px;
    left: -30px;

    color: white;
    font-size: 30px;
    text-shadow: 0 0 5px black;

    cursor: pointer;
}

canvas {
    //border: 2px solid;
}

//ninivert, September 2016

/*VARIABLES*/

canvas = document.getElementsByTagName('canvas')[0];
canvas.width = document.body.clientWidth;
canvas.height = document.body.clientHeight;

var ctx = canvas.getContext('2d');

/*Modify options here*/

//possible characters that will appear
var characterList = ['a', 'b', 'c', 'd', 'e', 'f', 'g', 'h', 'i', 'j', 'k', 'l', 'm', 'n', 'o', 'p', 'q', 'r', 's', 't', 'u', 'v', 'w', 'x', 'y', 'z'];

//stocks possible character attributes
var layers = {
    n: 5, //number of layers
    letters: [100, 40, 30, 20, 10], //letters per layer (starting from the deepest layer)
    coef: [0.1, 0.2, 0.4, 0.6, 0.8], //how much the letters move from the mouse (starting from the deepest layer)
    size: [16, 22, 36, 40, 46], //font size of the letters (starting from the deepest layer)
    color: ['#fff', '#eee', '#ccc', '#bbb', '#aaa'], //color of the letters (starting from the deepest layer)
    font: 'Courier' //font family (of every layer)
};

/*End of options*/

var characters = [];
var mouseX = document.body.clientWidth/2;
var mouseY = document.body.clientHeight/2;

var rnd = {
    btwn: function(min, max) {
        return Math.floor(Math.random() * (max - min) + min);
    },
    choose: function(list) {
        return list[rnd.btwn(0, list.length)];
    }
};

/*LETTER DRAWING*/

function drawLetter(char) {
    ctx.font = char.size + 'px ' + char.font;
    ctx.fillStyle = char.color;

    var x = char.posX + (mouseX-canvas.width/2)*char.coef;
    var y = char.posY + (mouseY-canvas.height/2)*char.coef;

    ctx.fillText(char.char, x, y);
}

/*ANIMATION*/

document.onmousemove = function(ev) {
    mouseX = ev.pageX - canvas.offsetLeft;
    mouseY = ev.pageY - canvas.offsetTop;

    if (window.requestAnimationFrame) {
        requestAnimationFrame(update);
    } else {
        update();
    }
};

function update() {
    clear();
    render();
}

function clear() {
    ctx.clearRect(0, 0, canvas.width, canvas.height);
}

function render() {
    for (var i = 0; i < characters.length; i++) {
        drawLetter(characters[i]);
    }
}

/*INITIALIZE*/

function createLetters() {
    for (var i = 0; i < layers.n; i++) {
        for (var j = 0; j < layers.letters[i]; j++) {

            var character = rnd.choose(characterList);
            var x = rnd.btwn(0, canvas.width);
            var y = rnd.btwn(0, canvas.height);

            characters.push({
                char: character,
                font: layers.font,
                size: layers.size[i],
                color: layers.color[i],
                layer: i,
                coef: layers.coef[i],
                posX: x,
                posY: y
            });

        }
    }
}

createLetters();
update();

/*REAJUST CANVAS AFTER RESIZE*/

window.onresize = function() {
    location.reload();
};

document.getElementById('close').onclick = function() {
    this.parentElement.style.visibility = 'hidden';
    this.parentElement.style.opacity = '0';
}

Ce que je veux

j'aurais voulu changer la police de carractère par une windings ou autre pour faire apparaîres des notes de musiques à la place des lettres et que celà couvre le fond (arriere) de ma page mais ne la repousse pas en dessous.
Merci encore pour votre disponibilité

Ce que j'obtiens

l'animation prend tout l'ecran et "repousse" mon site au dessous