bugfix: reader-nav is fully fixed; no settle-on-scroll (0.21.3)

frontend/src/routes/+layout.svelte

@@ -226,9 +226,9 @@
     main {
         padding: var(--space-4);
         /* Reserve room for the fixed header so its presence doesn't
-           overlap content. The min-height is a fallback that matches
-           the header at typical viewport sizes (60–72px); resize
-           observers would be more accurate but the gap is forgiving. */
+           overlap content. The header height comes from a runtime
+           ResizeObserver (see onMount above) so this always tracks
+           the rendered size. */
         padding-top: calc(var(--app-header-h) + var(--space-4));
         max-width: 64rem;
         margin: 0 auto;
@@ -236,6 +236,8 @@
     }
 
     :global(html[data-reader-fullscreen='true']) main {
-        padding-top: var(--space-4);
+        /* No top reservation in focus mode — the chapter image runs
+           edge-to-edge once the header has slid off. */
+        padding-top: 0;
     }
 </style>