[mercury] Remove elevation-1 default border and background

bun.lock

@@ -72,6 +72,7 @@
       "version": "0.1.0",
       "dependencies": {
         "oxc-resolver": "~11.10.0",
+        "sass": "~1.86.3",
       },
       "devDependencies": {
         "@eslint/js": "*",

packages/common/src/html.ts

@@ -86,7 +86,9 @@ export const CSS_CLASSES = {
   },
   TAB: {
     TAG: "ch-tab-render",
-    SELECTOR: "tab"
+    SELECTOR: "tab",
+    FILLED_LIST_SELECTOR: "tab-filled-list",
+    OUTLINED_SELECTOR: "tab-outlined"
   },
   TOOLTIP: {
     TAG: "ch-tooltip",
@@ -134,3 +136,16 @@ export const CUSTOM_CSS_ONLY_FOR_PREVIEW_LAYOUT = `.layout {
   font-size: var(--mer-font__size--xs);
   justify-content: center;
 }`;
+
+export const CONTENT_SLOT = {
+  /* Diagonal hatch pattern used as a visual placeholder for empty content areas */
+  SELECTOR: "content-slot",
+  CSS: `
+    background-color: transparent;
+    background-image: var(--content-slot-background-image);
+    block-size: 200px;
+    display: grid;
+    place-content: center;
+    margin: 0 !important;
+  `
+};