move all sidenote logic to Sidenote component

src/lib/Post.svelte

@@ -2,53 +2,18 @@
     import { onMount } from 'svelte';
     import { formatDate } from './datefmt.js';
     import { makeSlug } from '$lib/slug.js';
+    
     import Link from './Link.svelte';
     export { Link as a };
 </script>
 
 <script>
     export let title, date;
-
-    // deal with sidenote collisions
-    function tileNotes() {
-        const minNoteGap = 15;
-        // let sidenotes = Array.from(document.getElementsByClassName('sidenote'));
-        let notes = document.querySelectorAll('.sidenote');
-        if (window.getComputedStyle(notes[0]).position === 'fixed') {
-            // fixed position means we are in mobile territory, so 
-            // get rid of the overflow stuff and then exit
-            for (let note of notes) {
-                note.style.top = '';
-            }
-            return;
-        }
-
-        let labels = document.querySelectorAll('label.counter');
-        var prev = 0;
-        for (var i=0; i < notes.length; i++) {
-            let labelTop = labels[i].getBoundingClientRect().y + window.scrollY;
-            let noteHeight = notes[i].getBoundingClientRect().height;
-            if (labelTop < prev + minNoteGap) {
-                // there is a collision
-                notes[i].style.top = `${prev + minNoteGap}px`;
-                prev = prev + minNoteGap + noteHeight;
-            }
-            else {
-                // no collision
-                notes[i].style.top = `${labelTop}px`;
-                prev = labelTop + noteHeight;
-            }
-        }
-    }
-
-    onMount(async () => {
-        tileNotes();
-        window.addEventListener('resize', tileNotes);
-    });
 </script>
 
 <svelte:head>
     <title>{title}</title>
+    <link rel="stylesheet" href="/prism-dracula.css" />
 </svelte:head>
 
 <div id="post">

src/lib/Sidenote.svelte

@@ -87,12 +87,63 @@
     }
 </style>
 
-<script>
-    let id = Math.random().toString().slice(2);
+<script context="module">
+    import { browser } from '$app/env';
+    var sidenotes = {};
+
+    function tileNotes() {
+        // find and fix collisions between sidenotes
+        const minNoteGap = 15;
+        var prevBottom = 0;
+        Object.values(sidenotes).forEach(s => {
+            if (window.getComputedStyle(s.note).position === 'fixed') {
+                // fixed position means we are in mobile territory,
+                // so get rid of the overflow stuff
+                s.note.style.top = '';
+                return;
+            }
+
+            let labelTop = s.label.getBoundingClientRect().y + window.scrollY;
+            let noteHeight = s.note.getBoundingClientRect().height;
+            if (labelTop < prevBottom + minNoteGap) {
+                // there is a collision
+                s.note.style.top = `${prevBottom + minNoteGap}px`;
+                prevBottom = prevBottom + minNoteGap + noteHeight;
+            }
+            else {
+                // no collision, but these don't quite match otherwise
+                s.note.style.top = `${labelTop}px`;
+                prevBottom = labelTop + noteHeight;
+            }
+        })
+    }
+
+    if (browser) {
+        window.addEventListener('resize', tileNotes);
+    }
 </script>
 
-<label for={id} class="counter"></label>
+<script>
+    import { onMount } from 'svelte';
+
+    const id = Math.random().toString().slice(2);
+    sidenotes[id] = {mounted: false};
+    let label;
+    let note;
+
+    onMount(async () => {
+        sidenotes[id] = {mounted: true, label, note};
+        if (Object.values(sidenotes).every(n => n.mounted)) {
+            // all sidenotes have been mounted, now we can fix the collisions
+            tileNotes();
+        }
+
+        return () => sidenotes[id].mounted = false;
+    });
+</script>
+
+<label bind:this={label} for={id} class="counter"></label>
 <input type="checkbox" class="sidenote-toggle" {id}/>
-<span class="sidenote">
+<span bind:this={note} class="sidenote">
     <slot></slot>
 </span>