We are using highcharts and are trying to customize a chart to look similar to this:

We were able to set colors as documented and also increase the thickness of the lines by using the lineWidth attribute, but can’t find a way to customize the data points so they are always circles and larger than the thicker lines. This is what it looks like at this point:

Also, we can’t find a way to remove the default gray horizontal lines.
Help!
This gray line is called grid line, you can customize them following the reference.
To remove grid lines
Like this example.
Change marker width
demo
You can take a look here if you want to customize series markers.