feat(theme): add base styles

src/app/@theme/styles/pure/pure.custom.scss

@@ -0,0 +1,34 @@
+:host /deep/ {
+  color: $nga-color-default;
+
+  nga-layout {
+    nga-layout-header > nav {
+      box-shadow: 0 4px 12px 0 rgba(33, 57, 161, 0.08);
+    }
+
+    nga-sidebar {
+      box-shadow: 0 4px 12px 0 rgba(33, 57, 161, 0.08);
+
+      ul {
+        li a {
+          color: $nga-color-primary;
+          transition: all 0.2s ease;
+          padding: .87rem 0 .87rem 1rem;
+
+          &:hover {
+            background: $nga-color-default;
+          }
+
+          &.active {
+            font-weight: bold;
+          }
+        }
+      }
+    }
+
+    nga-layout-footer > nav {
+      box-shadow: 0 4px 12px 0 rgba(33, 57, 161, 0.08);
+      border: none !important;
+    }
+  }
+}

src/app/@theme/styles/pure/pure.redefines.scss

@@ -0,0 +1,20 @@
+@import '~@nga/theme/styles/themes/nga.theme.default';
+
+$nga-color-primary: #7d85b2;
+$nga-color-default: #edf1f7;
+$nga-color-secondary: #b5bbd5;
+
+$nga-background: white;
+
+$nga-layout-background: $nga-color-default;
+
+$nga-header-height: 4.725rem;
+$nga-header-background: $nga-background;
+
+$nga-footer-height: $nga-header-height;
+$nga-footer-background: $nga-background;
+
+$nga-user-picture-background: $nga-color-default;
+
+$nga-sidebar-background: $nga-background;
+$nga-sidebar-width: 16.25rem;

src/app/@theme/styles/pure/pure.theme.scss

@@ -1,3 +1,6 @@
 @import '~@nga/theme/styles/themes/nga.theme.default';
 
+@import 'pure.redefines';
+@import 'pure.custom';
+
 @include nga-theme();

src/app/@theme/styles/styles.scss

@@ -1 +1 @@
-@import "default.theme";
+@import "pure/pure.theme";