use proper variables for bp3 namespace

src/components/app.scss

@@ -5,7 +5,7 @@
 
 @import '../variables.scss';
 
-.bp3-dark .splitter-layout > .layout-splitter  {
+.#{$ns}-dark .splitter-layout > .layout-splitter  {
     // make layout splitter match app color scheme
     background-color: $pt-dark-app-background-color;
 }
@@ -15,7 +15,7 @@
     background-color: $pt-app-background-color;
 }
 
-.bp3-dark .terminal-padding {
+.#{$ns}-dark .terminal-padding {
     background-color: black;
 }
 

src/components/editor.scss

@@ -5,7 +5,7 @@
 
 @import '../variables.scss';
 
-.bp3-dark .ace_gutter {
+.#{$ns}-dark .ace_gutter {
     // make ace editor match app backgound color
     background-color: $pt-dark-app-background-color;
 }

src/components/status-bar.scss

@@ -20,7 +20,7 @@
     margin-left: 10px;
 }
 
-.bp3-progress-bar.status-bar-item {
+.#{$ns}-progress-bar.status-bar-item {
     // override progress bar default gray1 backgound
     background-color: $pt-app-background-color;
 }

src/components/toolbar.scss

@@ -3,7 +3,9 @@
 
 // Custom styling for the Toolbar control.
 
-.bp3-navbar-divider {
+@import '../variables.scss';
+
+.#{$ns}-navbar-divider {
     // don't draw vertical line since we are just using button groups
     border-left: unset;
 }