fix: Fix sidebar heading color with Appbar Package

Close #991

Author: equinusocio

.src/themes/darker/sidebar.json

@@ -9,9 +9,7 @@
     "layer0.opacity": 1.0,
     "layer0.draw_center": false,
     "layer0.inner_margin": [0, 24, 12, 24],
-    "content_margin": [0, 12, 0, 0],
-    "layer1.tint": [0,0,0],
-    "layer1.opacity": 0.0
+    "content_margin": [0, 12, 0, 0]
   },
   {
     "class": "sidebar_tree",

.src/themes/default/sidebar.json

@@ -10,9 +10,7 @@
     "layer0.tint": [<%= ui.background.primary.rgb %>],
     "layer0.opacity": 1.0,
     "layer0.draw_center": false,
-    "layer0.inner_margin": [0, 24, 12, 24],
-    "layer1.tint": [0,0,0],
-    "layer1.opacity": 0.0
+    "layer0.inner_margin": [0, 24, 12, 24]
   },
   {
     "class": "sidebar_tree",

Material-Theme-Darker.sublime-theme

@@ -530,9 +530,7 @@
       "layer0.opacity": 1.0,
       "layer0.draw_center": false,
       "layer0.inner_margin": [0, 24, 12, 24],
-      "content_margin": [0, 12, 0, 0],
-      "layer1.tint": [0,0,0],
-      "layer1.opacity": 0.0
+      "content_margin": [0, 12, 0, 0]
     },
     {
       "class": "sidebar_tree",

Material-Theme.sublime-theme

@@ -533,9 +533,7 @@
       "layer0.tint": [38, 50, 56],
       "layer0.opacity": 1.0,
       "layer0.draw_center": false,
-      "layer0.inner_margin": [0, 24, 12, 24],
-      "layer1.tint": [0,0,0],
-      "layer1.opacity": 0.0
+      "layer0.inner_margin": [0, 24, 12, 24]
     },
     {
       "class": "sidebar_tree",