.slider {
  width: 600px;
}

.axis path,
.axis line {
  stroke: black;  
}
 
path {
    stroke-width: 1;
    fill: none;
}
 
.line {
  stroke: red;
  stroke-width: 5;
  opacity: 0.6;
}

.line_reference {
  stroke: green;
  stroke-width: 5;
  opacity: 0.6;
}

.bar {
  fill: red;
  opacity: 0.8;
}

.area {
  fill: lightsteelblue;
  opacity: 0.5;
}

.x-axis, .y-axis {
  font-size: 1em;
  font-family: sans-serif;
}

.mean{
  stroke-dasharray: 5,5; 
  stroke-width: 2;
  stroke: lightgray;
}