From 89b8785a40f5ced765f9a2091bde84f448dd715e Mon Sep 17 00:00:00 2001
From: MechaCat02 <fabian@diekaulbachs.de>
Date: Sun, 17 May 2026 20:57:05 +0200
Subject: [PATCH] bugfix: reader-nav is fully fixed; no settle-on-scroll
 (0.21.3)

---
 backend/Cargo.lock                            |  2 +-
 backend/Cargo.toml                            |  2 +-
 frontend/package.json                         |  2 +-
 frontend/src/lib/styles/tokens.css            |  8 +-
 frontend/src/routes/+layout.svelte            | 10 ++-
 .../manga/[id]/chapter/[n]/+page.svelte       | 82 +++++++++++++------
 6 files changed, 73 insertions(+), 33 deletions(-)

diff --git a/backend/Cargo.lock b/backend/Cargo.lock
index e844c03..18b4001 100644
--- a/backend/Cargo.lock
+++ b/backend/Cargo.lock
@@ -1033,7 +1033,7 @@ checksum = "5e5032e24019045c762d3c0f28f5b6b8bbf38563a65908389bf7978758920897"
 
 [[package]]
 name = "mangalord"
-version = "0.21.2"
+version = "0.21.3"
 dependencies = [
  "anyhow",
  "argon2",
diff --git a/backend/Cargo.toml b/backend/Cargo.toml
index 7bb978c..3b2d8bf 100644
--- a/backend/Cargo.toml
+++ b/backend/Cargo.toml
@@ -1,6 +1,6 @@
 [package]
 name = "mangalord"
-version = "0.21.2"
+version = "0.21.3"
 edition = "2021"
 
 [lib]
diff --git a/frontend/package.json b/frontend/package.json
index 164feb5..32b2e81 100644
--- a/frontend/package.json
+++ b/frontend/package.json
@@ -1,6 +1,6 @@
 {
   "name": "mangalord-frontend",
-  "version": "0.21.2",
+  "version": "0.21.3",
   "private": true,
   "type": "module",
   "scripts": {
diff --git a/frontend/src/lib/styles/tokens.css b/frontend/src/lib/styles/tokens.css
index 2408b45..b1cad87 100644
--- a/frontend/src/lib/styles/tokens.css
+++ b/frontend/src/lib/styles/tokens.css
@@ -61,10 +61,12 @@
     --icon-lg: 22px;
 
     /* App-frame heights (fixed-position bars at the top and bottom of
-       the viewport). Used by the layout + reader to reserve content
-       space and animate fullscreen mode. Recomputed once if the
-       header padding/font-size ever changes — keep in sync. */
+       the viewport). These are first-paint fallbacks — the real
+       values are written by ResizeObservers on the actual elements
+       in +layout.svelte and the reader, so they reflect rendered
+       size and survive font / zoom / wrap changes. */
     --app-header-h: 60px;
+    --reader-nav-h: 56px;
     --reader-bar-h: 56px;
 
     --z-dropdown: 10;
diff --git a/frontend/src/routes/+layout.svelte b/frontend/src/routes/+layout.svelte
index dba595e..9a9a399 100644
--- a/frontend/src/routes/+layout.svelte
+++ b/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>
diff --git a/frontend/src/routes/manga/[id]/chapter/[n]/+page.svelte b/frontend/src/routes/manga/[id]/chapter/[n]/+page.svelte
index 166e7fc..59c23f2 100644
--- a/frontend/src/routes/manga/[id]/chapter/[n]/+page.svelte
+++ b/frontend/src/routes/manga/[id]/chapter/[n]/+page.svelte
@@ -69,6 +69,31 @@
     let index = $state(initialIndex);
     let continuousPageEls: HTMLImageElement[] = $state([]);
     let chapterBarEl: HTMLElement | undefined = $state();
+    let readerNavEl: HTMLElement | undefined = $state();
+
+    // Publish the reader nav's actual measured height. Sticky
+    // positioning had a "settle on scroll" effect: the bar's natural
+    // position sat 16px below the app header (main's space-4 padding),
+    // and only docked against the header once the user scrolled
+    // enough to consume that gap. The fix is to lift the bar out of
+    // document flow entirely (position: fixed) and reserve space in
+    // the chapter content via `--reader-nav-h`.
+    $effect(() => {
+        if (!readerNavEl) return;
+        const publish = () => {
+            document.documentElement.style.setProperty(
+                '--reader-nav-h',
+                `${readerNavEl!.offsetHeight}px`
+            );
+        };
+        publish();
+        const ro = new ResizeObserver(publish);
+        ro.observe(readerNavEl);
+        return () => {
+            ro.disconnect();
+            document.documentElement.style.removeProperty('--reader-nav-h');
+        };
+    });
 
     // Publish the bottom chapter-bar's actual measured height so the
     // continuous container's `padding-bottom` exactly matches it. Same
@@ -389,7 +414,7 @@
     <title>{pageTitle}</title>
 </svelte:head>
 
-<nav class="reader-nav" aria-label="reader">
+<nav class="reader-nav" aria-label="reader" bind:this={readerNavEl}>
     <a href="/manga/{manga.id}" class="back" data-testid="back-to-manga">
         <ArrowLeft size={18} aria-hidden="true" />
         {#if manga.cover_image_path}
@@ -605,45 +630,36 @@
 {/if}
 
 <style>
-    /* Sticky directly under the fixed layout header. `top: var(--app-header-h)`
-       pins the bar's top edge to the bottom edge of the layout
-       header so it never slides under it. Focus mode slides it up
-       off-screen via a transform AND clips its height to 0 so the
-       chapter pages get the full top of the viewport. */
+    /* Pinned to the viewport directly below the (also fixed) layout
+       header. `position: fixed` rather than `sticky` because the
+       latter would have a "settle on scroll" period until its natural
+       position consumes main's padding-top. Chapter content reserves
+       room for this bar via `--reader-nav-h` (measured at runtime by
+       a ResizeObserver in onMount). Focus mode slides it up
+       off-screen via transform — the fixed origin keeps the slide
+       distance equal to the bar's height regardless of scroll. */
     .reader-nav {
-        position: sticky;
+        position: fixed;
         top: var(--app-header-h);
+        left: 0;
+        right: 0;
         z-index: 10;
         display: flex;
         justify-content: space-between;
         align-items: center;
-        padding-top: var(--space-2);
-        padding-bottom: var(--space-2);
+        padding: var(--space-2) var(--space-4);
         border-bottom: 1px solid var(--border);
-        margin: 0 calc(-1 * var(--space-4)) var(--space-3);
-        padding-left: var(--space-4);
-        padding-right: var(--space-4);
         background: var(--bg);
         gap: var(--space-3);
         flex-wrap: wrap;
         transition:
             transform 220ms ease-out,
-            max-height 220ms ease-out,
-            opacity 220ms ease-out,
-            padding 220ms ease-out,
-            margin 220ms ease-out;
-        max-height: 200px;
-        overflow: hidden;
+            opacity 220ms ease-out;
     }
 
     :global(html[data-reader-fullscreen='true']) .reader-nav {
         transform: translateY(-100%);
-        max-height: 0;
-        padding-top: 0;
-        padding-bottom: 0;
-        margin-bottom: 0;
         opacity: 0;
-        border-bottom-color: transparent;
         pointer-events: none;
     }
 
@@ -763,17 +779,37 @@
         color: var(--text-muted);
     }
 
+    /* Reserve room for the fixed reader-nav above so the first page
+       image (single mode) and the top of the chapter stack
+       (continuous mode) aren't hidden behind it. The variable is
+       written by the ResizeObserver in onMount so the reservation
+       always matches actual rendered height. Focus mode collapses
+       the reservation in lockstep with the bar's slide-out. */
     .page-wrap {
         display: grid;
         grid-template-columns: auto 1fr auto;
         gap: var(--space-2);
         align-items: center;
+        padding-top: var(--reader-nav-h);
+        transition: padding-top 220ms ease-out;
     }
 
     .continuous {
         display: flex;
         flex-direction: column;
         align-items: center;
+        padding-top: var(--reader-nav-h);
+        transition:
+            padding-top 220ms ease-out,
+            padding-bottom 220ms ease-out;
+    }
+
+    :global(html[data-reader-fullscreen='true']) .page-wrap,
+    :global(html[data-reader-fullscreen='true']) .continuous {
+        padding-top: 0;
+    }
+    :global(html[data-reader-fullscreen='true']) .continuous {
+        padding-bottom: 0;
     }
 
     .page-image {