feat(integration): add image variants section and standardize code snippets

web/src/assets/main.css

@@ -389,18 +389,10 @@ body {
 	}
 }
 
-.shiki-block :where(pre.shiki) {
-	margin: 0;
-	padding: 0;
-	background-color: transparent !important;
-}
-
-.shiki-block :where(pre.shiki),
-.shiki-block :where(pre.shiki span) {
-	color: var(--shiki-light);
-}
-
-.dark .shiki-block :where(pre.shiki),
-.dark .shiki-block :where(pre.shiki span) {
-	color: var(--shiki-dark);
+.image-placeholder {
+	background: repeating-linear-gradient(
+		135deg,
+		var(--ui-bg-elevated) 0 8px,
+		var(--ui-bg-accented) 8px 16px
+	);
 }