client: show header link icon on mobile

client/components/preview/preview.module.css

@@ -110,3 +110,18 @@
 	max-width: 100%;
 	max-height: 350px;
 }
+
+@media screen and (max-width: 800px) {
+	.markdownPreview h1 a::after,
+	.markdownPreview h2 a::after,
+	.markdownPreview h3 a::after,
+	.markdownPreview h4 a::after,
+	.markdownPreview h5 a::after,
+	.markdownPreview h6 a::after {
+		content: "#";
+		font-size: 0.7em;
+		margin-left: 0.25em;
+		font-weight: normal;
+		filter: opacity(0.5);
+	}
+}