diff --git a/src/components/Header/Header.module.scss b/src/components/Header/Header.module.scss
index cbdf833..7996e52 100644
--- a/src/components/Header/Header.module.scss
+++ b/src/components/Header/Header.module.scss
@@ -224,11 +224,13 @@
     justify-content: center;
     z-index: 113;
     /* Desktop sets gap: 74px which pushes children past the viewport
-       on phones. Reset for mobile and clip any residual overflow. */
+       on phones. Reset for mobile. Don't add overflow-x: hidden here — it
+       forces overflow-y to auto, turning the fixed header into a scroll
+       container that clips the user-profile dropdown (which opens below it).
+       The root <html> already clips residual horizontal overflow. */
     gap: 0;
     max-width: 100vw;
     max-width: 100dvw;
-    overflow-x: hidden;
 
     .actions {
       display: block;
diff --git a/src/components/UserProfile/UserProfile.module.scss b/src/components/UserProfile/UserProfile.module.scss
index 18e6e9c..050eb7c 100644
--- a/src/components/UserProfile/UserProfile.module.scss
+++ b/src/components/UserProfile/UserProfile.module.scss
@@ -26,7 +26,7 @@
   .dropdown {
     position: absolute;
     top: calc(100% + 8px);
-    right: 24px;
+    right: 0;
     min-width: 180px;
     background-image: url('/keepsimple_/assets/user-dropdown/white-bg.png');
     background-size: cover;
@@ -36,6 +36,10 @@
     z-index: 200;
     display: flex;
     flex-direction: column;
+    // The home hero <video> is GPU-composited while playing and can paint over
+    // this menu even though z-index puts it on top; promoting the dropdown to
+    // its own layer forces the compositor to honour that order.
+    transform: translateZ(0);
   }
 
   .userNameDropdown {
diff --git a/src/components/library/organisms/InteractiveCover/InteractiveCover.module.scss b/src/components/library/organisms/InteractiveCover/InteractiveCover.module.scss
index 82a4002..b790983 100644
--- a/src/components/library/organisms/InteractiveCover/InteractiveCover.module.scss
+++ b/src/components/library/organisms/InteractiveCover/InteractiveCover.module.scss
@@ -78,6 +78,26 @@ $cover-aspect-ultrawide: calc(4000 / 852);
   }
 }
 
+// Mobile (<768px): a fixed 448px portrait band. The hotspot layer isn't
+// rendered below 768px (see InteractiveCover.tsx `isWide`), so the cover is a
+// static image — the 3:2 art is covered into the box, cropping left/right.
+@media (max-width: 767px) {
+  .frame {
+    aspect-ratio: auto;
+    height: 448px;
+    max-height: none;
+  }
+
+  .image {
+    left: 0;
+    transform: none;
+    width: 100%;
+    height: 100%;
+    max-width: none;
+    object-fit: cover;
+  }
+}
+
 .trigger {
   position: absolute;
   margin: 0;
diff --git a/src/components/library/organisms/LibraryToolbar/LibraryToolbar.module.scss b/src/components/library/organisms/LibraryToolbar/LibraryToolbar.module.scss
index ae06a64..655d412 100644
--- a/src/components/library/organisms/LibraryToolbar/LibraryToolbar.module.scss
+++ b/src/components/library/organisms/LibraryToolbar/LibraryToolbar.module.scss
@@ -17,6 +17,12 @@
   height: 1px;
   background: var(--black-100);
   margin: 16px 0;
+
+  // Mobile: collapse the top margin so the divider connects to the fixed
+  // header (paired with the layout wrapper dropping its top padding).
+  @media (max-width: 768px) {
+    margin-top: 0;
+  }
 }
 
 .controls {
@@ -229,7 +235,7 @@
 
   @media (max-width: 768px) {
     width: 100%;
-    justify-content: flex-end;
+    justify-content: flex-start;
   }
 }
 
diff --git a/src/components/library/organisms/ObjectOverviewModal/ObjectOverviewModal.module.scss b/src/components/library/organisms/ObjectOverviewModal/ObjectOverviewModal.module.scss
index fa3dfdd..3a84b1b 100644
--- a/src/components/library/organisms/ObjectOverviewModal/ObjectOverviewModal.module.scss
+++ b/src/components/library/organisms/ObjectOverviewModal/ObjectOverviewModal.module.scss
@@ -359,6 +359,11 @@
     grid-template-columns: 1fr;
     gap: 24px;
     padding: 20px 16px;
+    // Stacked single-column grid in a flex:1 (full-height) body: grid's default
+    // align-content stretches the auto rows to fill leftover vertical space,
+    // ballooning `.actions` and `.left` far past their content. Pack rows to the
+    // top so each sizes to its content; extra space stays at the bottom.
+    align-content: start;
   }
 
   // Keep the cover from swallowing the screen on tall portrait art.
diff --git a/src/components/library/organisms/ShareSelectionPanel/ShareSelectionPanel.module.scss b/src/components/library/organisms/ShareSelectionPanel/ShareSelectionPanel.module.scss
index a3a338f..d32fb4a 100644
--- a/src/components/library/organisms/ShareSelectionPanel/ShareSelectionPanel.module.scss
+++ b/src/components/library/organisms/ShareSelectionPanel/ShareSelectionPanel.module.scss
@@ -82,6 +82,38 @@
   background: transparent !important;
 }
 
+// Mobile: the two action buttons crammed beside the heading squeezed the
+// "Share selection via link" label into a 3-line wrap. Stack the buttons under
+// one another, and pin each label to one 14px line.
+@media (max-width: 768px) {
+  .header {
+    gap: 16px;
+    padding: 16px;
+  }
+
+  .actions {
+    flex-direction: column;
+    align-items: stretch;
+    gap: 12px;
+  }
+
+  .actions button {
+    width: 100%;
+    justify-content: center;
+
+    span {
+      font-size: 14px;
+      white-space: nowrap;
+    }
+  }
+
+  // Two stacked buttons make the header taller than the desktop 87px bar, so
+  // grow the collapsed cap to fit it — otherwise the lower button is clipped.
+  .collapsed {
+    max-height: 120px;
+  }
+}
+
 // Fills the space under the header and clips its content as the panel collapses
 // (the panel's max-height drives the accordion). `flex: 1` + `min-height: 0`
 // let .body scroll when the panel hits its 440px cap with many objects.
diff --git a/src/components/library/organisms/Shelf/Shelf.module.scss b/src/components/library/organisms/Shelf/Shelf.module.scss
index 2604243..1497e48 100644
--- a/src/components/library/organisms/Shelf/Shelf.module.scss
+++ b/src/components/library/organisms/Shelf/Shelf.module.scss
@@ -96,6 +96,45 @@
     .button {
       color: var(--brown);
     }
+
+    // Mobile: split the cramped single row into two. Promote `.right`'s children
+    // into the header's flex flow (display: contents) so a zero-height full-width
+    // break can drop the two action buttons onto their own row:
+    //   Row 1: settings + type icon + name (left)  ·  count (right)
+    //   Row 2: Select shelf (left)  ·  Add object (right)
+    @media (max-width: 768px) {
+      flex-wrap: wrap;
+
+      .right {
+        display: contents;
+      }
+
+      .left {
+        order: 1;
+        min-width: 0;
+      }
+
+      .count {
+        order: 2;
+      }
+
+      &::after {
+        content: '';
+        flex-basis: 100%;
+        height: 0;
+        order: 3;
+      }
+
+      .selectShelfWrap {
+        order: 4;
+        margin-top: 12px;
+      }
+
+      .addWrap {
+        order: 5;
+        margin-top: 12px;
+      }
+    }
   }
 
   .content {
@@ -158,6 +197,22 @@
       z-index: 0;
       pointer-events: none;
 
+      // Mobile: pull the board wider past both edges so it spans the narrow
+      // viewport. left/right set the box, so width is implied — drop the
+      // desktop fill-available width and its negative margin.
+      @media (max-width: 768px) {
+        left: -148px;
+        right: -35px;
+        width: auto;
+        margin-right: 0;
+
+        // The box is now sized by left/right (width: auto), so the inherited
+        // `auto` would shrink the board to its intrinsic width — fill instead.
+        img {
+          width: 100%;
+        }
+      }
+
       img {
         width: inherit;
       }
diff --git a/src/components/library/organisms/Shelf/Shelf.tsx b/src/components/library/organisms/Shelf/Shelf.tsx
index 7751bbd..c4f6d04 100644
--- a/src/components/library/organisms/Shelf/Shelf.tsx
+++ b/src/components/library/organisms/Shelf/Shelf.tsx
@@ -234,11 +234,22 @@ export function Shelf(props: ShelfProps): JSX.Element {
 
   const isOverflowing = canScrollLeft || canScrollRight;
 
-  // Page the row by most of a viewport, matching the LibraryToolbar jump arrows.
+  // Advance one card per click. The stride is the distance between two adjacent
+  // slots (card width + gap); with a single card fall back to its own width, and
+  // with none to most of a viewport.
   const scrollJump = (direction: -1 | 1) => {
     const el = itemsRef.current;
     if (!el) return;
-    el.scrollBy({ left: direction * el.clientWidth * 0.8, behavior: 'smooth' });
+    const slots = cardsRef.current?.children;
+    let step = el.clientWidth * 0.8;
+    if (slots && slots.length > 0) {
+      const first = slots[0] as HTMLElement;
+      step =
+        slots.length > 1
+          ? (slots[1] as HTMLElement).offsetLeft - first.offsetLeft
+          : first.offsetWidth;
+    }
+    el.scrollBy({ left: direction * step, behavior: 'smooth' });
   };
 
   const closeRename = useCallback(() => {
diff --git a/src/layouts/library/Home/Home.module.scss b/src/layouts/library/Home/Home.module.scss
index c526154..0a14f38 100644
--- a/src/layouts/library/Home/Home.module.scss
+++ b/src/layouts/library/Home/Home.module.scss
@@ -21,9 +21,12 @@
     // context, so the button needs to sit above them to stay clickable.
     z-index: 4;
 
-    @media (max-width: 590px) {
-      top: 20px;
-      left: 16px;
+    // Mobile: the cover is a full-bleed 448px band under the fixed 55px header.
+    // Center the button and sit it 22px below the header (55 + 22).
+    @media (max-width: 767px) {
+      top: 77px;
+      left: 50%;
+      transform: translateX(-50%);
       max-width: calc(100% - 32px);
     }
   }
diff --git a/src/layouts/library/Library/Library.module.scss b/src/layouts/library/Library/Library.module.scss
index ed299dd..d53f7ab 100644
--- a/src/layouts/library/Library/Library.module.scss
+++ b/src/layouts/library/Library/Library.module.scss
@@ -7,6 +7,12 @@
     min-height: calc(100vh - 168px);
   }
 
+  // Mobile: drop the top padding so the sticky toolbar's divider sits flush
+  // against the fixed header instead of floating below a 16px gap.
+  @media (max-width: 768px) {
+    padding-top: 0;
+  }
+
   // Fill the viewport below the 48px sticky header so the content centers in the
   // real available space rather than the top 60vh (which sat it too high).
   .empty {
