fix: Adjusts styling of tooltip icons in dark-mode (#784)

Author: aprouja1

src/devtools/style/global.styl

@@ -182,3 +182,6 @@ $arrow-color = $vue-ui-color-dark
         fill #444
         .vue-ui-dark-mode &
           fill #666
+
+.vue-ui-dark-mode .tooltip .vue-ui-icon svg
+  fill #666