diff --git a/d3_resources/SpectrumChartD3.css b/d3_resources/SpectrumChartD3.css
index fffad90..bfe30b3 100644
--- a/d3_resources/SpectrumChartD3.css
+++ b/d3_resources/SpectrumChartD3.css
@@ -251,24 +251,32 @@ svg.SpectrumChartD3 {
 .scalerheader{ fill: rgba(185,185,185,0.80); fill-opacity: 0.55; }
 .activescaler > g > .scalerheader{ fill: #909090; fill-opacity: 0.95; }
   
-  .SpectrumChartD3 .scalertxt{
-    fill: var(--d3spec-text-color, black);
-  }
-  .scaleraxis {
-    stroke-opacity: 0.8;
-    fill-opacity: 0.3;
-    stroke: var(--d3spec-axis-color, black);
-  }
-  
-  .scalertoggle {
-    stroke: var(--d3spec-axis-color, black);
-  }
-  
+.SpectrumChartD3 .scalertxt{
+  fill: var(--d3spec-text-color, black);
+}
+.scaleraxis {
+  stroke-opacity: 0.8;
+  fill-opacity: 0.3;
+  stroke: var(--d3spec-axis-color, black);
+}
   
-  .leftbuttonzoombox {
-    fill: #666;
-    fill-opacity: 0.25;
-  }
+.scalertoggle {
+  stroke: var(--d3spec-axis-color, black);
+}
+
+.BackgroundScaler .scaleraxis, .BackgroundScaler .scalertoggle {
+  fill: var(--d3spec-back-line-color, black);
+}
+
+.SecondaryScaler .scaleraxis.secondary, .SecondaryScaler .scalertoggle.secondary {
+  fill: var(--d3spec-second-line-color, black);
+}
+
+
+.leftbuttonzoombox {
+  fill: #666;
+  fill-opacity: 0.25;
+}
   
   .leftbuttonzoomoutboxy {
     fill: #666;
diff --git a/d3_resources/SpectrumChartD3.js b/d3_resources/SpectrumChartD3.js
index 77b28c6..02540a7 100644
--- a/d3_resources/SpectrumChartD3.js
+++ b/d3_resources/SpectrumChartD3.js
@@ -6325,12 +6325,17 @@ SpectrumChartD3.prototype.drawScalerBackgroundSecondary = function() {
     if (spectrumScaleFactor != null && spectrumScaleFactor >= 0) {
       scalenum += 1;
       
-      let speccolor = spectrum.lineColor ? spectrum.lineColor : 'black';
+      const speccolor = spectrum.lineColor; //If null, will use CSS variables
       
       var spectrumSliderArea = self.scalerWidgetBody.append("g")
         .attr("id", spectrumSelector + "SliderArea")
         .attr("transform","translate(" + 20*(scalenum-1) + "," + ypos + ")");
-
+          
+      if( spectrum.type === self.spectrumTypes.BACKGROUND )
+        spectrumSliderArea.attr("class", "BackgroundScaler");
+      else if( spectrum.type === self.spectrumTypes.SECONDARY )
+        spectrumSliderArea.attr("class", "SecondaryScaler");
+        
       spectrum.sliderText = spectrumSliderArea.append("text")
         .attr("class", "scalertxt")
         .attr("x", 0)