fix sidenote tiling bug

src/lib/Sidenote.svelte

@@ -7,11 +7,13 @@
     .counter {
         counter-increment: sidenote;
         color: #444;
+        margin-left: 0.05rem;
 
         &:after {
             font-size: 0.75rem;
             position: relative;
             bottom: 0.3rem;
+            color: #8c0606;
         }
     }
 
@@ -23,6 +25,7 @@
             position: relative;
             font-size: 0.75rem;
             bottom: 0.2rem;
+            color: #8c0606;
         }
     }
 
@@ -103,7 +106,14 @@
                 return;
             }
 
-            let labelTop = s.label.getBoundingClientRect().y + window.scrollY;
+            let labelTop = s.label.getBoundingClientRect().y;
+            if (labelTop === 0) {
+                // sometimes we get spurious results, only in dev mode though
+                // I think it's related to hot module reloading
+                return;
+            }
+            labelTop += window.scrollY;
+
             let noteHeight = s.note.getBoundingClientRect().height;
             if (labelTop < prevBottom + minNoteGap) {
                 // there is a collision