scatter chart: enable configuring color opacity of points

I'm struggling with configuration of opacity of colors in scatter plot. No matter how I change `color` and `colors`, opacity of points is still set to random (or at least that's what I feel it is). I'd like to a) either be able to configure it myself b) or disable it completely and let all points have same opacity.

Is this possible somehow?

I appreciate any kind of feedback, thank you!

Sample data:

```
data: {
json: json_data,
keys: {
value: ["date", "hours"]
},
x: 'date',
xFormat: '%Y-%m-%d',
type: 'scatter',
color: function(color, d){ return "#ddd"; },
colors: { // has no effect
hours: '#ff0000',
date: '#00ff00'
}
};
```