feat: adjust width & thickness of pip scrubber

src/viewerModule/nehuba/viewerCtrl/perspectiveViewSlider/perspectiveViewSlider.style.css

@@ -50,14 +50,17 @@ img
 
 .scrubber
 {
+    --scrubber-width: 0.28rem;
+
+    opacity: 0.7;
     pointer-events: none;
     width: 100%;
     height: 100%;
     display: inline-block;
 
     border-style: solid;
-    border-width: 0 0 0 0.5rem;
-    margin-left: -0.25rem;
+    border-width: 0 0 0 var(--scrubber-width);
+    margin-left: calc(var(--scrubber-width) * -0.5);
 
     border-color: rgba(10, 10, 10, 0.5);
 }
@@ -72,8 +75,8 @@ img
     background-color: red;
     display: inline-block;
     height: 100%;
-    width: 0.5rem;
-    margin-left: -0.5rem;
+    width: var(--scrubber-width);
+    margin-left: calc(var(--scrubber-width) * -1);
 }