html, body {
    margin: 0;
    padding: 0;
    overflow: hidden;
}
canvas {
    display: block;
}

/* Add style to checkRedWhenCollide checkbox */
#checkRedWhenCollide {
    font-family: halvetica, serif;
}

.prevent-select {
    -webkit-user-select: none; /* Safari */
    -ms-user-select: none; /* IE 10 and IE 11 */
    user-select: none; /* Standard syntax */
}