fix collection filters, hero spacing, sale filter, and error page CSS

- collection filter bar: horizontal scroll on mobile instead of wrapping
  across 3 rows, smaller pills at mobile sizes
- add sale collection filter at /collections/sale (filters on_sale products)
- hero :page variant: add consistent top padding (var(--space-2xl))
- contact page: remove redundant top padding (hero handles it now)
- error page: fix CSS path from /assets/app.css to /assets/css/app.css
  (broken in production due to asset fingerprinting)

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

PROGRESS.md

@@ -59,16 +59,16 @@ Issues found during hands-on testing of the deployed prod site on mobile and des
 - [x] Footer social icons should match the "Find me on" icons from the contact page
 
 ### Collections / all products
-- [ ] Categories on all-products page are too spaced out
+- [x] Categories on all-products page are too spaced out
 
 ### Content pages
-- [ ] Hero title spacing differs between content pages (about, delivery, etc.) — contact is fine
+- [x] Hero title spacing differs between content pages (about, delivery, etc.) — contact is fine
 
 ### Sale / filtering
-- [ ] Should there be a "Sale" section or filter for discounted products?
+- [x] Should there be a "Sale" section or filter for discounted products?
 
 ### Errors
-- [ ] 404 page is broken
+- [x] 404 page is broken (CSS path was wrong — `/assets/app.css` instead of `/assets/css/app.css`)
 
 ### Search (deferred — after usability fixes)
 - [ ] Search doesn't work (modal opens but no results/functionality) — see [docs/plans/search.md](docs/plans/search.md)

lib/simpleshop_theme_web/components/page_templates/contact.html.heex

@@ -10,7 +10,7 @@
   cart_status={assigns[:cart_status]}
   active_page="contact"
 >
-  <main id="main-content" class="max-w-4xl mx-auto px-4 sm:px-6 lg:px-8 py-16">
+  <main id="main-content" class="max-w-4xl mx-auto px-4 sm:px-6 lg:px-8 pb-16">
     <.hero_section
       variant={:page}
       title="Get in touch"

lib/simpleshop_theme_web/components/shop_components/product.ex

@@ -568,7 +568,7 @@ defmodule SimpleshopThemeWeb.ShopComponents.Product do
           />
         </section>
       <% :page -> %>
-        <div class="text-center">
+        <div class="text-center" style="padding-top: var(--space-2xl);">
           <h1
             class="text-4xl md:text-5xl font-bold mb-6"
             style="font-family: var(--t-font-heading); color: var(--t-text-primary); font-weight: var(--t-heading-weight); letter-spacing: var(--t-heading-tracking);"

lib/simpleshop_theme_web/controllers/error_html.ex

@@ -66,7 +66,7 @@ defmodule SimpleshopThemeWeb.ErrorHTML do
         <meta charset="utf-8" />
         <meta name="viewport" content="width=device-width, initial-scale=1" />
         <title>{@error_code} - {@error_title}</title>
-        <link phx-track-static rel="stylesheet" href={~p"/assets/app.css"} />
+        <link phx-track-static rel="stylesheet" href={~p"/assets/css/app.css"} />
         <style id="theme-css">
           <%= Phoenix.HTML.raw(@generated_css) %>
         </style>

lib/simpleshop_theme_web/live/shop_live/collection.ex

@@ -49,6 +49,11 @@ defmodule SimpleshopThemeWeb.ShopLive.Collection do
     {:ok, "All Products", nil, PreviewData.products()}
   end
 
+  defp load_collection("sale") do
+    sale_products = Enum.filter(PreviewData.products(), & &1.on_sale)
+    {:ok, "Sale", :sale, sale_products}
+  end
+
   defp load_collection(slug) do
     case PreviewData.category_by_slug(slug) do
       nil -> :not_found
@@ -59,7 +64,11 @@ defmodule SimpleshopThemeWeb.ShopLive.Collection do
   @impl true
   def handle_event("sort_changed", %{"sort" => sort}, socket) do
     slug =
-      if socket.assigns.current_category, do: socket.assigns.current_category.slug, else: "all"
+      case socket.assigns.current_category do
+        nil -> "all"
+        :sale -> "sale"
+        category -> category.slug
+      end
 
     {:noreply, push_patch(socket, to: ~p"/collections/#{slug}?sort=#{sort}")}
   end
@@ -99,7 +108,13 @@ defmodule SimpleshopThemeWeb.ShopLive.Collection do
         <div class="max-w-7xl mx-auto px-4 sm:px-6 lg:px-8 py-8">
           <.collection_filter_bar
             categories={@categories}
-            current_slug={@current_category && @current_category.slug}
+            current_slug={
+              case @current_category do
+                :sale -> "sale"
+                nil -> nil
+                cat -> cat.slug
+              end
+            }
             sort_options={@sort_options}
             current_sort={@current_sort}
           />
@@ -111,7 +126,7 @@ defmodule SimpleshopThemeWeb.ShopLive.Collection do
                 theme_settings={@theme_settings}
                 mode={@mode}
                 variant={:default}
-                show_category={@current_category == nil}
+                show_category={@current_category in [nil, :sale]}
               />
             <% end %>
           </.product_grid>
@@ -136,14 +151,14 @@ defmodule SimpleshopThemeWeb.ShopLive.Collection do
 
   defp collection_filter_bar(assigns) do
     ~H"""
-    <div class="flex flex-wrap items-center justify-between gap-4 mb-8">
+    <div class="flex flex-wrap items-center justify-between gap-3 mb-6">
-      <nav aria-label="Collection filters">
+      <nav aria-label="Collection filters" class="overflow-x-auto -mx-4 px-4 sm:mx-0 sm:px-0">
-        <ul class="flex flex-wrap gap-2">
+        <ul class="flex gap-1.5 sm:flex-wrap sm:gap-2">
-          <li>
+          <li class="shrink-0">
             <.link
               navigate={collection_path("all", @current_sort)}
               class={[
-                "px-4 py-2 rounded-full text-sm transition-colors",
+                "px-3 py-1.5 sm:px-4 sm:py-2 rounded-full text-xs sm:text-sm whitespace-nowrap transition-colors",
                 if(@current_slug == nil, do: "font-medium", else: "hover:opacity-80")
               ]}
               style={
@@ -156,12 +171,29 @@ defmodule SimpleshopThemeWeb.ShopLive.Collection do
               All
             </.link>
           </li>
+          <li class="shrink-0">
+            <.link
+              navigate={collection_path("sale", @current_sort)}
+              class={[
+                "px-3 py-1.5 sm:px-4 sm:py-2 rounded-full text-xs sm:text-sm whitespace-nowrap transition-colors",
+                if(@current_slug == "sale", do: "font-medium", else: "hover:opacity-80")
+              ]}
+              style={
+                if(@current_slug == "sale",
+                  do: "background-color: var(--t-accent); color: var(--t-text-on-accent);",
+                  else: "background-color: var(--t-surface-raised); color: var(--t-text-primary);"
+                )
+              }
+            >
+              Sale
+            </.link>
+          </li>
           <%= for category <- @categories do %>
-            <li>
+            <li class="shrink-0">
               <.link
                 navigate={collection_path(category.slug, @current_sort)}
                 class={[
-                  "px-4 py-2 rounded-full text-sm transition-colors",
+                  "px-3 py-1.5 sm:px-4 sm:py-2 rounded-full text-xs sm:text-sm whitespace-nowrap transition-colors",
                   if(@current_slug == category.slug, do: "font-medium", else: "hover:opacity-80")
                 ]}
                 style={
@@ -183,7 +215,7 @@ defmodule SimpleshopThemeWeb.ShopLive.Collection do
           name="sort"
           options={@sort_options}
           selected={@current_sort}
-          class="px-4 py-2 text-sm"
+          class="px-3 py-1.5 sm:px-4 sm:py-2 text-xs sm:text-sm"
           aria-label="Sort products"
         />
       </form>