drawWave = (line, y) => {
context.beginPath()
context.lineWidth = 0.2
context.strokeStyle = colors.bg
context.fillStyle = waveGradient(y)
d3.area()
.x1(([x, y]) => x)
.y0(height)
.y1(([x, y]) => y)
.curve(d3.curveBasis)
.context(context)(line)
context.fill()
context.stroke()
context.closePath()
}