Use header Markdown decorations as anchor links

lib/markdown.ts

@@ -1,6 +1,4 @@
 import MarkdownIt from "markdown-it";
-import StateCore from "markdown-it/lib/rules_core/state_core";
-import MarkdownItAnchor from "markdown-it-anchor";
 import slugify from "@sindresorhus/slugify";
 import * as util from "./util";
 

site/css/main.scss

@@ -98,6 +98,7 @@ article {
 			content: "#";
 			font-family: $monospace;
 			color: var(--accent-color);
+			user-select: none;
 		}
 
 		> a {
@@ -134,6 +135,7 @@ article {
 			.header-anchor {
 				font-family: $monospace;
 				color: var(--accent-color);
+				user-select: none;
 
 				&::before, &::after { content: ""; }
 			}