.x.axis line, .x.axis path {stroke:black;}
.y.axis line, .y.axis path {stroke:red;}
.axis line, .axis path {shape-rendering:crispEdges; fill:none;}
.y.axis text {fill:red;}
text.y.title {fill:red;}
path.line {stroke-width:2; fill:none;}
/* adding invisible stroke border to make the point easier to drag */
circle.control {stroke-width:20; stroke:black; stroke-opacity:0; cursor:move;}
circle.intersection {stroke:black; fill:white; stroke-width:2;}