start of UI fixes

src/routes/+page.svelte

@@ -72,6 +72,7 @@
 {#if !$mapStore.composing}
     <button
     class="fab"
+    class:shifted={isMobile && $mapStore.selectedMessage}
     onclick={() => mapStore.set(
         {selectedMessage: null, composing: true })}>
     +
@@ -119,6 +120,12 @@
     align-items:center;
     justify-content: center;
     line-height: 1;
+    transition: bottom 0.35s cubic-bezier(0.32, 0.72, 0, 1); /* match the sheet's slide timing */
+}
+
+/* lift it above the bottom sheet so it doesn't get covered, x position stays the same */
+.fab.shifted {
+    bottom: 35vh;
 }
 
 </style>