fix(segment-button): remove border for standalone

this also fixes some sass lint errors

packages/core/src/components/nav/nav.scss

@@ -13,7 +13,7 @@ ion-nav {
   width: 100%;
   height: 100%;
 
-  background-color: black;
+  background-color: #000;
 
   contain: layout size style;
 

packages/core/src/components/segment-button/segment-button.scss

@@ -19,6 +19,8 @@ ion-segment-button {
 
   overflow: hidden;
 
+  border: 0;
+
   text-decoration: none;
   text-overflow: ellipsis;
   white-space: nowrap;

packages/core/src/components/select/select.scss

@@ -77,4 +77,4 @@ ion-select {
 .item-label-stacked .select,
 .item-label-floating .select {
   max-width: 100%;
-}
+}

packages/core/src/components/text/text.ios.scss

@@ -16,4 +16,4 @@
     color: $base-color !important;
   }
 
-}
+}

packages/core/src/components/text/text.md.scss

@@ -16,4 +16,4 @@
     color: $base-color !important;
   }
 
-}
+}