diff --git a/web/kyushu_compare.html b/web/kyushu_compare.html
index de9244d..1df9111 100644
--- a/web/kyushu_compare.html
+++ b/web/kyushu_compare.html
@@ -513,7 +513,8 @@ function prepareLightArcCanvas(){
 function canvasArcAngle(degrees,bearing){
   return (degrees + bearing - 90) * Math.PI / 180;
 }
-function drawCaArc(ctx,x,y,radius,startDeg,endDeg,bearing,color,width){
+function drawCaArc(ctx,x,y,radius,startDeg,endDeg,bearing,color,width,alpha){
+  ctx.save();
   ctx.beginPath();
   ctx.arc(
     x,y,radius,
@@ -522,9 +523,11 @@ function drawCaArc(ctx,x,y,radius,startDeg,endDeg,bearing,color,width){
     false
   );
   ctx.strokeStyle=color;
+  ctx.globalAlpha=alpha==null?1:alpha;
   ctx.lineWidth=width;
   ctx.lineCap="butt";
   ctx.stroke();
+  ctx.restore();
 }
 
 function drawCaLeg(ctx,x,y,length,degrees,bearing){
@@ -535,7 +538,8 @@ function drawCaLeg(ctx,x,y,length,degrees,bearing){
   ctx.moveTo(x,y);
   ctx.lineTo(x+length*Math.cos(angle),y+length*Math.sin(angle));
   ctx.strokeStyle=CA_COLOR.CHBLK;
-  ctx.lineWidth=2;
+  ctx.globalAlpha=0.82;
+  ctx.lineWidth=1.35;
   ctx.stroke();
   ctx.restore();
 }
@@ -570,8 +574,12 @@ function drawLightArcFeature(ctx,feature,bearing,width,height){
   if(end<=start)end+=360;
   const arcColor=CA_COLOR[args.length>=8?args[2]:props.s52_arc_color] || CA_COLOR.CHMGD;
   const outlineColor=CA_COLOR[args.length>=8?args[0]:props.s52_arc_outline_color] || CA_COLOR.OUTLW;
-  drawCaArc(ctx,point.x,point.y,radius,start,end,bearing,outlineColor,metrics.arcWidth+metrics.outlineWidth);
-  drawCaArc(ctx,point.x,point.y,radius,start,end,bearing,arcColor,metrics.arcWidth);
+  // Keep the S-52 CA radius/angles intact, but map millimetre pen widths to a
+  // lighter screen preview.  Raw OUTLW=4 can otherwise dominate the chart.
+  const visualArcWidth=Math.max(1.6,Math.min(3.0,metrics.arcWidth*0.90));
+  const visualOutlineExtra=Math.max(2.6,Math.min(4.2,metrics.outlineWidth*0.38));
+  drawCaArc(ctx,point.x,point.y,radius,start,end,bearing,outlineColor,visualArcWidth+visualOutlineExtra,0.88);
+  drawCaArc(ctx,point.x,point.y,radius,start,end,bearing,arcColor,visualArcWidth,0.94);
   if(sectorRadius>0){
     drawCaLeg(ctx,point.x,point.y,sectorRadius,start,bearing);
     drawCaLeg(ctx,point.x,point.y,sectorRadius,end,bearing);