fix: align homepage section titles and unify download button color

- Wrap the Categories and Popular sections in the same responsive
  max-width container (820/1080/1180) used by Official and Latest, so all
  four section titles line up vertically on desktop.
- Official carousel arrows: hide the arrow at the edge already reached, and
  snap one card per click (reveal the next/previous card fully, keeping a
  small peek) instead of a fixed-pixel scroll.
- Show the pagination dots on desktop too (was mobile-only).
- RecommendedCard download button icon: text-ark-gold -> text-white to match
  the file bubble / popular / video download buttons.

Desktop-scoped; mobile layout unchanged.

Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>

src/pages/Home/index.tsx

@@ -196,8 +196,39 @@ export function Home() {
     };
   }, [rec.length]);
 
+  // Reveal one more card per click, fully, inside the arrow "lanes" (the left
+  // and right padding the arrows float in) so the edge card is never half-shown
+  // or tucked under an arrow.
+  //  - Right arrow: bring the first card clipped on the right so its RIGHT edge
+  //    rests just left of the right arrow.
+  //  - Left arrow: bring the last card clipped on the left so its LEFT edge
+  //    rests just right of the left arrow.
   const scrollRec = (dir: 1 | -1) => {
-    recRowRef.current?.scrollBy({ left: dir * 280, behavior: "smooth" });
+    const row = recRowRef.current;
+    if (!row) return;
+    const children = Array.from(row.children) as HTMLElement[];
+    if (children.length === 0) return;
+    const rowLeft = row.getBoundingClientRect().left;
+    const style = getComputedStyle(row);
+    const padLeft = parseFloat(style.paddingLeft) || 0;
+    const padRight = parseFloat(style.paddingRight) || 0;
+    const epsilon = 2;
+    let delta: number;
+    if (dir === 1) {
+      const laneRight = row.clientWidth - padRight;
+      const next = children
+        .map((c) => c.getBoundingClientRect().right - rowLeft)
+        .find((right) => right > laneRight + epsilon);
+      delta = next !== undefined ? next - laneRight : 0;
+    } else {
+      const lefts = children
+        .map((c) => c.getBoundingClientRect().left - rowLeft)
+        .filter((left) => left < padLeft - epsilon);
+      delta = lefts.length ? lefts[lefts.length - 1] - padLeft : -row.scrollLeft;
+    }
+    const maxScroll = Math.max(0, row.scrollWidth - row.clientWidth);
+    const target = Math.max(0, Math.min(maxScroll, row.scrollLeft + delta));
+    row.scrollTo({ left: target, behavior: "smooth" });
   };
 
   useEffect(() => {
@@ -241,6 +272,7 @@ export function Home() {
 
       <Reveal delay={0}>
         <section id="categories" className="scroll-mt-16 md:scroll-mt-24">
+          <div className="mx-auto max-w-full md:max-w-[820px] lg:max-w-[1080px] xl:max-w-[1180px]">
           <div className="px-4 md:px-0">
             <SectionHeader
               title={t("categorySection")}
@@ -331,6 +363,7 @@ export function Home() {
               </Reveal>
             ))}
           </div>
+          </div>
         </section>
       </Reveal>
 
@@ -358,7 +391,7 @@ export function Home() {
               ))}
             </div>
             <div
-              className="flex h-[30px] items-center justify-center gap-1.5 md:hidden"
+              className="flex h-[30px] items-center justify-center gap-1.5"
               aria-label="Recommended pagination"
             >
               {Array.from({ length: recommendedDotCount }).map((_, index) => (
@@ -439,15 +472,17 @@ export function Home() {
       {hasPopular ? (
         <Reveal>
           <section id="popular" className="scroll-mt-16 md:scroll-mt-24">
-            <div className="px-4 md:px-0">
-              <SectionHeader
-                title={t("popularSection")}
-                viewAllTo="/browse?sort=popular"
-                viewAllLabel={t("viewAll")}
-              />
-            </div>
-            <div className="mt-2.5 md:mt-7">
-              <PopularRankList posts={popularPosts} categories={cats} />
+            <div className="mx-auto max-w-full md:max-w-[820px] lg:max-w-[1080px] xl:max-w-[1180px]">
+              <div className="px-4 md:px-0">
+                <SectionHeader
+                  title={t("popularSection")}
+                  viewAllTo="/browse?sort=popular"
+                  viewAllLabel={t("viewAll")}
+                />
+              </div>
+              <div className="mt-2.5 md:mt-7">
+                <PopularRankList posts={popularPosts} categories={cats} />
+              </div>
             </div>
           </section>
         </Reveal>