UX: add fadeout to topic list on large vp

* Changing the category & tag dropdown back into their original form.
The breadcrumb idea isn't working well.

| BC | AC |
|--------|--------|
| ![CleanShot 2025-06-09 at 18 59
37@2x](https://github.com/user-attachments/assets/cbeb3aaf-ad0e-4085-8548-58ea0a521c95)
| ![CleanShot 2025-06-09 at 18 57
33@2x](https://github.com/user-attachments/assets/15db752b-4983-4b7f-b6f8-9a8ded9e6f9f)
|

* Alignment fix in chat navbar drawer

| BC | AC |
|--------|--------|
| ![CleanShot 2025-06-09 at 18 59
18@2x](https://github.com/user-attachments/assets/38c7dcee-dc77-4a44-ae8d-5ecb7910536b)
| ![CleanShot 2025-06-09 at 18 58
36@2x](https://github.com/user-attachments/assets/be699f88-4e5e-4d8c-ab4d-f6d1eca93037)
|

.discourse-compatibility

@@ -0,0 +1,2 @@
+< 3.5.0.beta5-dev: 31249c4f27d93e83c6b83d42d93974522a9a612e
+

Gemfile.lock

@@ -15,16 +15,16 @@ GEM
       tzinfo (~> 2.0, >= 2.0.5)
       uri (>= 0.13.1)
     ast (2.4.3)
-    base64 (0.2.0)
-    benchmark (0.4.0)
-    bigdecimal (3.1.9)
+    base64 (0.3.0)
+    benchmark (0.4.1)
+    bigdecimal (3.2.2)
     concurrent-ruby (1.3.5)
     connection_pool (2.5.3)
-    drb (2.2.1)
+    drb (2.2.3)
     i18n (1.14.7)
       concurrent-ruby (~> 1.0)
-    json (2.11.3)
-    language_server-protocol (3.17.0.4)
+    json (2.12.2)
+    language_server-protocol (3.17.0.5)
     lint_roller (1.1.0)
     logger (1.7.0)
     minitest (5.25.5)
@@ -35,10 +35,10 @@ GEM
     prettier_print (1.2.1)
     prism (1.4.0)
     racc (1.8.1)
-    rack (3.1.13)
+    rack (3.1.15)
     rainbow (3.1.1)
     regexp_parser (2.10.0)
-    rubocop (1.75.4)
+    rubocop (1.76.0)
       json (~> 2.3)
       language_server-protocol (~> 3.17.0.2)
       lint_roller (~> 1.1.0)
@@ -46,10 +46,10 @@ GEM
       parser (>= 3.3.0.2)
       rainbow (>= 2.2.2, < 4.0)
       regexp_parser (>= 2.9.3, < 3.0)
-      rubocop-ast (>= 1.44.0, < 2.0)
+      rubocop-ast (>= 1.45.0, < 2.0)
       ruby-progressbar (~> 1.7)
       unicode-display_width (>= 2.4.0, < 4.0)
-    rubocop-ast (1.44.1)
+    rubocop-ast (1.45.0)
       parser (>= 3.3.7.2)
       prism (~> 1.4)
     rubocop-capybara (2.22.1)
@@ -67,12 +67,12 @@ GEM
     rubocop-factory_bot (2.27.1)
       lint_roller (~> 1.1)
       rubocop (~> 1.72, >= 1.72.1)
-    rubocop-rails (2.31.0)
+    rubocop-rails (2.32.0)
       activesupport (>= 4.2.0)
       lint_roller (~> 1.1)
       rack (>= 1.1)
       rubocop (>= 1.75.0, < 2.0)
-      rubocop-ast (>= 1.38.0, < 2.0)
+      rubocop-ast (>= 1.44.0, < 2.0)
     rubocop-rspec (3.6.0)
       lint_roller (~> 1.1)
       rubocop (~> 1.72, >= 1.72.1)
@@ -99,4 +99,4 @@ DEPENDENCIES
   syntax_tree
 
 BUNDLED WITH
-   2.6.8
+   2.6.9

about.json

@@ -6,9 +6,7 @@
   "learn_more": "https://meta.discourse.org/t/installing-a-theme-or-theme-component/63682",
   "theme_version": "0.0.1",
   "modifiers": {
-    "svg_icons": [
-      "fire"
-    ],
+    "svg_icons": ["fire"],
     "serialize_topic_is_hot": true
   },
   "color_schemes": {

common/head_tag.html

@@ -1,6 +1,7 @@
 <script>
-  if(!CSS.supports("(color: hsl(from white h s l))")){
+  if (!CSS.supports("(color: hsl(from white h s l))")) {
     window.unsupportedBrowser = true;
-    window.I18n.translations[I18n.locale].js.browser_update = 'The Horizon theme does not support your browser. Please update your browser, or <a href="?safe_mode=no_themes">switch to safe mode</a>.';
+    window.I18n.translations[I18n.locale].js.browser_update =
+      'The Horizon theme does not support your browser. Please update your browser, or <a href="?safe_mode=no_themes">switch to safe mode</a>.';
   }
 </script>

javascripts/discourse/components/card/topic-activity-column.gjs

@@ -1,9 +1,7 @@
 import Component from "@glimmer/component";
-import avatar from "discourse/helpers/avatar";
 import concatClass from "discourse/helpers/concat-class";
 import icon from "discourse/helpers/d-icon";
 import formatDate from "discourse/helpers/format-date";
-import { i18n } from "discourse-i18n";
 
 export default class TopicActivityColumn extends Component {
   get topicUser() {
@@ -27,37 +25,34 @@ export default class TopicActivityColumn extends Component {
       };
     } else if (this.args.topic.posts_count === 1) {
       return {
-        user: this.args.topic.creator,
-        username: this.args.topic.creator.username,
-        activityText: "user_posted",
-        class: "--posted",
+        user: this.args.topic.firstPosterUser,
+        username: this.args.topic.last_poster_username,
+        class: "--created",
       };
+    } else {
+      return;
     }
   }
 
   <template>
     <span class={{concatClass "topic-activity" this.topicUser.class}}>
-      <div class="topic-activity__user">
+      <div class="topic-activity__type">
         {{#if this.topicUser.user}}
-          {{avatar this.topicUser.user imageSize="small"}}
+          {{icon "reply"}}
         {{else}}
           {{icon "pencil"}}
         {{/if}}
       </div>
+
       {{#if this.topicUser.username}}
         <span
           class="topic-activity__username"
         >{{this.topicUser.username}}</span>
+        <span class="dot-separator"></span>
       {{/if}}
-      <div class="topic-activity__reason">
-        {{i18n (themePrefix this.topicUser.activityText)}}
-      </div>
+
       <div class="topic-activity__time">
-        {{formatDate
-          @topic.bumpedAt
-          leaveAgo="true"
-          format="medium-with-ago-and-on"
-        }}
+        {{formatDate @topic.bumpedAt leaveAgo="true" format="tiny"}}
       </div>
     </span>
   </template>

javascripts/discourse/components/card/topic-creator-column.gjs

@@ -0,0 +1,19 @@
+import Component from "@glimmer/component";
+import avatar from "discourse/helpers/avatar";
+
+export default class TopicCreatorColumn extends Component {
+  get topicCreator() {
+    return {
+      user: this.args.topic.creator,
+      username: this.args.topic.creator.username,
+      class: "--topic-creator",
+    };
+  }
+
+  <template>
+    <div class={{this.topicUser.class}}>
+      {{avatar this.topicCreator.user}}
+      <span class="topic-creator__username">{{this.topicUser.username}}</span>
+    </div>
+  </template>
+}

javascripts/discourse/components/card/topic-replies-column.gjs

@@ -1,5 +1,5 @@
+import { gt } from "truth-helpers";
 import icon from "discourse/helpers/d-icon";
-import gt from "truth-helpers/helpers/gt";
 
 const TopicRepliesColumn = <template>
   {{#if (gt @topic.replyCount 1)}}

javascripts/discourse/components/sidebar-new-topic-button.gjs

@@ -5,9 +5,8 @@ import didInsert from "@ember/render-modifiers/modifiers/did-insert";
 import didUpdate from "@ember/render-modifiers/modifiers/did-update";
 import willDestroy from "@ember/render-modifiers/modifiers/will-destroy";
 import { service } from "@ember/service";
-import { gt } from "truth-helpers";
+import { gt, not } from "truth-helpers";
 import CreateTopicButton from "discourse/components/create-topic-button";
-import not from "truth-helpers/helpers/not";
 
 export default class SidebarNewTopicButton extends Component {
   @service composer;

javascripts/discourse/initializers/topic-list-columns.gjs

@@ -1,6 +1,7 @@
 import { withPluginApi } from "discourse/lib/plugin-api";
 import TopicActivityColumn from "../components/card/topic-activity-column";
 import TopicCategoryColumn from "../components/card/topic-category-column";
+import TopicCreatorColumn from "../components/card/topic-creator-column";
 import TopicLikesColumn from "../components/card/topic-likes-column";
 import TopicRepliesColumn from "../components/card/topic-replies-column";
 import TopicStatusColumn from "../components/card/topic-status-column";
@@ -30,6 +31,12 @@ const TopicLikesReplies = <template>
   </td>
 </template>;
 
+const TopicCreator = <template>
+  <td class="topic-creator-data">
+    <TopicCreatorColumn @topic={{@topic}} />
+  </td>
+</template>;
+
 export default {
   name: "topic-list-customizations",
 
@@ -52,6 +59,10 @@ export default {
             item: TopicLikesReplies,
             after: "topic-author-avatar",
           });
+          columns.add("topic-creator", {
+            item: TopicCreator,
+            after: "topic-author-avatar",
+          });
           columns.delete("views");
           columns.delete("replies");
           if (!router.currentRouteName.includes("userPrivateMessages")) {

package.json

@@ -1,11 +1,11 @@
 {
   "private": true,
   "devDependencies": {
-    "@discourse/lint-configs": "2.11.1",
-    "ember-template-lint": "7.0.1",
-    "eslint": "9.22.0",
+    "@discourse/lint-configs": "2.25.0",
+    "ember-template-lint": "7.8.1",
+    "eslint": "9.28.0",
     "prettier": "3.5.3",
-    "stylelint": "16.16.0"
+    "stylelint": "16.20.0"
   },
   "engines": {
     "node": ">= 22",

scss/box-view.scss

@@ -1,4 +1,6 @@
-@media screen and (min-width: 1300px) {
+@use "lib/viewport";
+
+@media screen and (width >= 1300px) {
   #main-outlet {
     border-top-right-radius: var(--d-border-radius-large);
     border-top-left-radius: var(--d-border-radius-large);
@@ -20,7 +22,7 @@
 .has-full-page-chat .chat-replying-indicator-container {
   margin-bottom: var(--main-grid-gap);
 
-  @include breakpoint(medium) {
+  @include viewport.until(lg) {
     margin-bottom: 0;
   }
 }
@@ -28,7 +30,7 @@
 .has-full-page-chat .chat-selection-management {
   margin-bottom: var(--main-grid-gap);
 
-  @include breakpoint(medium) {
+  @include viewport.until(lg) {
     margin-bottom: 0;
   }
 }
@@ -40,17 +42,16 @@
   margin: 0;
   padding: 0;
   position: relative;
-  container: content-width / inline-size;
 
-  @include breakpoint(medium) {
+  @include viewport.until(lg) {
     display: none;
   }
 
-  @media screen and (max-width: 488px) {
+  @media screen and (width <= 488px) {
     display: none;
   }
 
-  @include breakpoint(tablet) {
+  @include viewport.until(md) {
     display: none;
   }
 
@@ -93,7 +94,7 @@
     bottom: var(--main-grid-gap);
     left: var(--left-distance);
 
-    @media screen and (max-width: 768px) {
+    @media screen and (width <= 768px) {
       bottom: calc(var(--d-border-radius-large) * 2);
     }
   }
@@ -103,7 +104,7 @@
     bottom: var(--main-grid-gap);
     left: calc(var(--right-distance) - var(--d-border-radius-large));
 
-    @media screen and (max-width: 768px) {
+    @media screen and (width <= 768px) {
       bottom: calc(var(--d-border-radius-large) * 2);
     }
   }
@@ -117,7 +118,7 @@
     left: var(--left-distance);
     height: var(--main-grid-gap);
 
-    @media screen and (max-width: 768px) {
+    @media screen and (width <= 768px) {
       height: calc(var(--d-border-radius-large) * 2);
     }
 
@@ -157,7 +158,7 @@
   }
 }
 
-@media screen and (min-width: 768px) {
+@media screen and (width >= 768px) {
   .with-topic-progress {
     bottom: calc(
       env(safe-area-inset-bottom) + var(--composer-height, 0px) +
@@ -166,7 +167,7 @@
   }
 }
 
-@media screen and (max-width: 768px) {
+@media screen and (width <= 768px) {
   .with-topic-progress {
     bottom: calc(
       env(safe-area-inset-bottom) + var(--composer-height, 0px) +
@@ -175,7 +176,7 @@
   }
 }
 
-@media screen and (max-width: 400px) {
+@media screen and (width <= 400px) {
   .with-topic-progress {
     bottom: calc(env(safe-area-inset-bottom) + var(--composer-height, 0px));
   }

scss/chat.scss

@@ -5,7 +5,9 @@
 }
 
 .c-navbar-container {
-  padding: 0 1.5em;
+  .full-page-chat & {
+    padding: 0 1.5em;
+  }
   background-color: var(--d-content-background);
 }
 
@@ -21,6 +23,10 @@ body.has-full-page-chat {
   .chat-drawer.is-expanded & {
     border: none;
   }
+
+  .c-navbar__title {
+    padding-left: 0.33em; // visual alignment for chat index, which does not havea a backarrow
+  }
 }
 
 .chat-drawer-outlet-container {

scss/color-exploration.scss

@@ -6,7 +6,7 @@
   --d-sidebar-header-icon-color: var(--d-sidebar-link-color);
   --d-sidebar-active-suffix-color: var(--d-sidebar-suffix-color);
   --d-sidebar-background: var(--background-color);
-  --d-sidebar-footer-fade: rgba(var(--tertiary-50-rgb), 1);
+  --d-sidebar-footer-fade: rgb(var(--tertiary-50-rgb), 1);
   --d-sidebar-prefix-background: var(--d-selected);
   --d-sidebar-active-prefix-background: light-dark(
     oklch(from var(--d-selected) calc(l * 0.85) c h),

scss/composer-peek-mode.scss

@@ -2,7 +2,7 @@
   display: none;
 }
 
-@media screen and (min-width: 1300px) {
+@media screen and (width >= 1300px) {
   html:not(.fullscreen-composer) {
     .peek-mode-toggle svg {
       transform: scaleX(-1);

scss/composer.scss

@@ -1,3 +1,5 @@
+@use "lib/viewport";
+
 #reply-control
   .select-kit.dropdown-select-box.composer-actions
   .select-kit-header {
@@ -12,7 +14,7 @@
 }
 
 #reply-control.hide-preview:not(.draft) {
-  @include breakpoint("mobile-extra-large", $rule: min-width) {
+  @include viewport.from(sm) {
     background: var(--d-content-background);
     border-top-right-radius: var(--d-border-radius);
     border-top-left-radius: var(--d-border-radius);

scss/desktop-full-width.scss

@@ -1,3 +1,5 @@
+@use "lib/viewport";
+
 // Full width layout. Ported from the Discourse Full Width theme component here
 // https://meta.discourse.org/t/discourse-full-width-component/292496, which we
 // intend to move into core over time.
@@ -23,7 +25,7 @@ $sidebar-width: 17em;
   body:not(.has-sidebar-page) & {
     max-width: unset;
 
-    @include breakpoint("mobile-extra-large") {
+    @include viewport.until(sm) {
       max-width: 25vw;
     }
   }
@@ -103,7 +105,7 @@ $sidebar-width: 17em;
         grid-area: extra-info;
         white-space: nowrap;
 
-        @include breakpoint("tablet") {
+        @include viewport.until(md) {
           display: none;
         }
       }
@@ -127,7 +129,7 @@ $sidebar-width: 17em;
         // at narrower widths, when 1fr = 0
         // we can center without matching the sidebar's width
         // which allows the title to take up the remaining width
-        @media screen and (max-width: 1400px) {
+        @media screen and (width <= 1400px) {
           grid-template-columns:
             calc(var(--d-sidebar-width) - 11px)
             1fr
@@ -136,7 +138,7 @@ $sidebar-width: 17em;
             auto;
         }
 
-        @media screen and (max-width: 1000px) {
+        @media screen and (width <= 1000px) {
           gap: 0.5em;
         }
 
@@ -189,11 +191,11 @@ $sidebar-width: 17em;
 .header-search--enabled .floating-search-input-wrapper {
   grid-area: extra-info;
 
-  @include breakpoint(tablet) {
+  @include viewport.until(md) {
     grid-area: rspace;
   }
 
-  @include breakpoint(mobile-extra-large) {
+  @include viewport.until(sm) {
     display: none;
   }
 }
@@ -208,7 +210,7 @@ body.has-sidebar-page {
     padding: 0;
   }
 
-  @media screen and (min-width: calc($reply-area-max-width + ($sidebar-width * 2))) {
+  @media screen and (width >= calc($reply-area-max-width + ($sidebar-width * 2))) {
     #reply-control.show-preview {
       margin-left: auto;
       margin-right: auto;
@@ -219,7 +221,7 @@ body.has-sidebar-page {
     }
   }
 
-  @media screen and (max-width: calc($reply-area-max-width + ($sidebar-width * 2))) and (min-width: calc($reply-area-max-width + calc($sidebar-width / 2))) {
+  @media screen and (width <= calc($reply-area-max-width + ($sidebar-width * 2))) and (width >= calc($reply-area-max-width + calc($sidebar-width / 2))) {
     #reply-control.show-preview:not(.fullscreen) {
       margin-left: $sidebar-width;
       width: auto;
@@ -265,7 +267,7 @@ body.sidebar-animate {
 }
 
 // provides some extra space for login buttons
-@media screen and (min-width: 1400px) {
+@media screen and (width >= 1400px) {
   .anon {
     .d-header .panel {
       grid-column-start: -4;

scss/desktop-horizon-fixes.scss

@@ -1,8 +1,8 @@
 // Fixing bulk select (only needed for desktop)
 .bulk-select-enabled {
-  .topic-list-header .topic-list-data.default {
-    position: sticky;
-    top: 10em;
+  .topic-list-header {
+    position: relative;
+    top: 0;
   }
 
   .topic-author-avatar-data {
@@ -13,7 +13,7 @@
     grid-area: bulk-select;
     margin-left: -0.5em;
 
-    @media screen and (max-width: 576px) {
+    @media screen and (width <= 576px) {
       margin-top: 0;
 
       label {
@@ -47,19 +47,19 @@
     }
   }
 
+  // bulk select
   .bulk-select-topics {
     position: absolute;
-    right: -1em;
+    right: 0;
     background: var(--secondary);
     border-radius: 0 0 0 var(--d-border-radius);
-    padding: 1em;
-
-    @media screen and (max-width: 1048px) {
-      right: 0;
-    }
+    display: flex;
+    gap: 0.5rem;
+    margin: 0.5rem;
 
     button {
       white-space: nowrap;
+      margin: 0;
     }
   }
 }

scss/header.scss

@@ -1,8 +1,10 @@
+@use "lib/viewport";
+
 .d-header {
   box-shadow: none;
   background: var(--background-color);
 
-  @include breakpoint(extra-large, $rule: min-width) {
+  @include viewport.from(xl) {
     padding-bottom: var(--main-grid-gap);
   }
 }

scss/main.scss

@@ -1,3 +1,5 @@
+@use "lib/viewport";
+
 :root {
   --main-grid-gap: 0.5em;
 }
@@ -5,7 +7,7 @@
 html:not(:has(.has-full-page-chat)) {
   background-color: var(--background-color);
 
-  @include breakpoint("mobile-extra-large") {
+  @include viewport.until(sm) {
     background-color: var(--d-content-background);
   }
 }
@@ -13,7 +15,7 @@ html:not(:has(.has-full-page-chat)) {
 body {
   -webkit-font-smoothing: antialiased;
 
-  @include breakpoint("mobile-extra-large") {
+  @include viewport.until(sm) {
     background-color: var(--d-content-background);
   }
 }
@@ -35,7 +37,7 @@ body.has-full-page-chat:not(.has-sidebar-page) {
   #main-outlet-wrapper {
     gap: var(--main-grid-gap);
 
-    @include breakpoint(medium) {
+    @include viewport.until(lg) {
       gap: 0;
     }
   }
@@ -50,22 +52,22 @@ body.has-sidebar-page #main-outlet-wrapper {
 }
 
 body:not(.has-sidebar-page) #main-outlet-wrapper {
-  @include breakpoint(medium, $rule: min-width) {
+  @include viewport.from(lg) {
     grid-template-columns: 0 minmax(0, 1fr) 0;
   }
 }
 
 body:not(.has-full-page-chat, .wizard) {
-  @include breakpoint(extra-large, $rule: min-width) {
+  @include viewport.from(xl) {
     background-color: var(--background-color);
   }
 
   #main-outlet-wrapper {
-    @include breakpoint(medium) {
+    @include viewport.until(lg) {
       --main-grid-gap: 0;
     }
 
-    @media screen and (min-width: 768px) {
+    @media screen and (width >= 768px) {
       gap: var(--main-grid-gap);
     }
 
@@ -76,7 +78,7 @@ body:not(.has-full-page-chat, .wizard) {
       border-radius: var(--d-border-radius-large);
       background-color: var(--d-content-background);
 
-      @include breakpoint(medium) {
+      @include viewport.until(lg) {
         border-radius: 0;
       }
 
@@ -85,7 +87,7 @@ body:not(.has-full-page-chat, .wizard) {
       }
 
       > *:not(.experimental-screen, .activate-account) {
-        @include breakpoint(medium, $rule: min-width) {
+        @include viewport.from(lg) {
           box-sizing: border-box;
           max-width: 1000px;
           margin-inline: auto;
@@ -98,7 +100,7 @@ body:not(.has-full-page-chat, .wizard) {
 
 #list-area {
   .show-more.has-topics {
-    @include breakpoint(medium, $rule: min-width) {
+    @include viewport.from(lg) {
       width: auto;
       right: 50%;
       transform: translateX(50%);

scss/misc.scss

@@ -71,7 +71,7 @@ input[type="color"]:focus,
   background-color: var(--background-color);
 }
 
-@include breakpoint(mobile-extra-large) {
+@include viewport.until(sm) {
   // pinned topic excerpts are hidden on small screens too
   .fk-d-menu__trigger.topic-list-layout-trigger {
     display: none;

scss/mobile-stuff.scss

@@ -1,5 +1,7 @@
+@use "lib/viewport";
+
 // temp separate file to avoid merge hell… to be distributed later
-@include breakpoint(medium) {
+@include viewport.until(lg) {
   html,
   .d-header {
     background-color: var(--d-content-background);
@@ -8,19 +10,19 @@
 
 #main-outlet-wrapper {
   *[class*="navigation-"] & {
-    @include breakpoint(mobile-extra-large) {
+    @include viewport.until(sm) {
       padding: 0;
     }
   }
 }
 
 #main-outlet {
-  @include breakpoint(mobile-extra-large) {
+  @include viewport.until(sm) {
     padding-top: var(--spacing-block-sm);
   }
 
   .list-controls {
-    @include breakpoint(mobile-extra-large) {
+    @include viewport.until(sm) {
       padding-inline: var(
         --spacing-inline-m
       ) !important; // override will be fixed when the whole chat page shenanigans is resolved
@@ -29,14 +31,13 @@
     }
 
     .navigation-container {
-      @include breakpoint(mobile-extra-large) {
+      @include viewport.until(sm) {
         gap: var(--spacing-inline-s);
 
-        // don't know why we even hide this crucial navigation on mobile
         .category-breadcrumb.hidden,
         .category-breadcrumb {
           display: flex !important;
-          column-gap: var(--spacing-inline-s);
+          column-gap: var(--spacing-inline-m);
           row-gap: var(--spacing-block-xs);
           flex-basis: 100%;
 
@@ -47,9 +48,12 @@
             ); // 2px is width of the outline
           }
 
+          .select-kit-header-wrapper {
+            gap: 0.25em;
+          }
+
           .select-kit-header {
             background: var(--d-content-background);
-            border: 0;
           }
         }
 
@@ -77,13 +81,13 @@
       #navigation-bar,
       .navigation-controls,
       .category-breadcrumb {
-        @include breakpoint(mobile-extra-large) {
+        @include viewport.until(sm) {
           margin-bottom: 0;
         }
       }
 
       .navigation-controls {
-        @include breakpoint(mobile-extra-large) {
+        @include viewport.until(sm) {
           gap: var(--spacing-inline-s);
         }
       }
@@ -91,12 +95,12 @@
   }
 
   .list-container {
-    @include breakpoint(mobile-extra-large) {
+    @include viewport.until(sm) {
       padding-inline: 0 !important;
     }
 
     .topic-list-body {
-      @include breakpoint(mobile-extra-large) {
+      @include viewport.until(sm) {
         border-top: 0;
         padding-top: 0;
       }
@@ -104,7 +108,7 @@
   }
 
   #topic-title {
-    @include breakpoint(mobile-extra-large) {
+    @include viewport.until(sm) {
       padding-inline: var(--spacing-inline-s) !important;
 
       .title-wrapper {
@@ -158,7 +162,7 @@
   }
 
   .container.posts {
-    @include breakpoint(mobile-extra-large) {
+    @include viewport.until(sm) {
       padding-inline: var(--spacing-inline-xs) !important;
 
       .main-avatar .avatar {
@@ -197,7 +201,7 @@
   }
 
   #topic-footer-buttons {
-    @include breakpoint(mobile-extra-large) {
+    @include viewport.until(sm) {
       padding-inline: var(--spacing-inline-xs) !important;
     }
   }

scss/nav-pills.scss

@@ -1,14 +1,36 @@
+@use "lib/viewport";
 .list-controls {
   position: sticky;
   top: var(--header-offset);
   background: var(--d-content-background);
   z-index: z("base");
-  padding: 1.5rem 0 1rem 0;
+  padding: 1.5rem 0 0 0;
   max-width: unset;
 
+  @include viewport.until(sm) {
+    padding-bottom: 1em;
+  }
+
   .navigation-container {
+    position: relative;
     gap: 1rem;
 
+    @include viewport.from(sm) {
+      &:after {
+        content: "";
+        position: absolute;
+        left: 0;
+        right: 0;
+        bottom: -1rem;
+        height: 1rem;
+        background: linear-gradient(
+          to bottom,
+          var(--d-content-background),
+          transparent
+        );
+      }
+    }
+
     .category-breadcrumb {
       order: 1;
     }
@@ -17,7 +39,7 @@
   .combo-box .combo-box-header {
     // needs more specificity than just in the button file
     background-color: var(--secondary);
-    border-radius: var(--d-border-radius-large);
+    border-radius: var(--d-border-radius);
     border: 1px solid var(--primary-300);
 
     &:hover {

scss/sidebar.scss

@@ -2,7 +2,7 @@
 
 .sidebar-wrapper,
 .sidebar-hamburger-dropdown {
-  @include breakpoint(medium) {
+  @include viewport.until(lg) {
     background: var(--secondary);
 
     .sidebar-footer-wrapper {
@@ -38,11 +38,11 @@
 }
 
 .sidebar-section-wrapper {
-  @include breakpoint(extra-large, $rule: min-width) {
+  @include viewport.from(xl) {
     padding-block: 0.45em;
   }
 
-  @include breakpoint(mobile-extra-large) {
+  @include viewport.until(sm) {
     .hamburger-panel .revamped & {
       margin-bottom: var(--spacing-block-m);
     }
@@ -57,7 +57,7 @@
     display: flex;
     flex-direction: column;
 
-    @include breakpoint(extra-large, $rule: min-width) {
+    @include viewport.from(xl) {
       gap: var(--spacing-block-xs);
     }
   }

scss/topic-cards.scss

@@ -1,3 +1,5 @@
+@use "lib/viewport";
+
 .topic-list .topic-list-item-separator {
   display: none;
 }
@@ -14,110 +16,107 @@
   border: none;
   display: flex;
   flex-direction: column;
-  gap: 1em;
+  gap: 1.25em;
 
-  @include breakpoint(medium) {
+  @include viewport.until(lg) {
     gap: 0.5em;
     padding: 0 0.5em;
   }
 
-  @include breakpoint(mobile-extra-large) {
+  @include viewport.until(sm) {
     gap: 0;
     padding: 0;
   }
 }
 
 .topic-list-body .topic-list-item {
+  position: relative;
+  background: var(--d-content-background);
+  box-shadow: 0 0 12px 1px var(--topic-card-shadow);
   text-overflow: ellipsis;
   padding: 0.75em 1rem;
   border: 1px solid var(--primary-300);
   display: grid;
-  grid-template-columns: 20px min-content min-content auto min-content;
-  grid-template-rows: auto minmax(20px, auto);
+  grid-template-columns: min-content min-content auto min-content;
   grid-template-areas:
-    ". . . . status"
-    "activity . . likes-replies category";
-  grid-column-gap: 12px;
-  grid-row-gap: 8px;
+    "creator title title status"
+    "creator category activity likes-replies";
+  grid-column-gap: 0.75rem;
+  grid-row-gap: 0.5rem;
   border-radius: var(--d-border-radius);
   cursor: pointer;
 
-  td.main-link .link-top-line {
-    grid-row: 1/2;
-    grid-column: 1/-1;
-    font-weight: 500;
-  }
-
-  &.--has-status-card td.main-link .link-top-line {
-    grid-column: 1/-2;
-  }
-
-  @include breakpoint(extra-large) {
+  .bulk-select-enabled & {
+    grid-template-columns: min-content min-content min-content auto min-content;
     grid-template-areas:
-      ". . . . status"
-      "activity . . likes-replies category";
+      "bulk-select creator title title status"
+      "bulk-select creator category activity likes-replies";
   }
 
-  @include breakpoint(mobile-extra-large) {
-    td.main-link .link-top-line,
-    &.--has-status-card td.main-link .link-top-line {
-      grid-row: 2/3;
-      grid-column: 1/-1;
-    }
-    grid-template-columns: 20px repeat(5, 1fr);
-    grid-template-rows: auto auto auto;
+  @include viewport.until(sm) {
     grid-template-areas:
-      "category category category category category status"
-      ". . . . . ."
-      "activity . . . . likes-replies";
+      "category category category status"
+      "creator title title title"
+      "activity activity activity likes-replies";
+    row-gap: 0.75em;
     border: none;
     border-bottom: 1px solid var(--primary-200);
     box-shadow: none;
     border-radius: 0;
   }
 
-  &.excerpt-expanded {
-    grid-template-columns: 20px auto auto min-content min-content;
-    grid-template-rows: auto auto auto;
-    grid-template-areas:
-      ". . . . status"
-      "activity . . . ."
-      "excerpt excerpt excerpt likes-replies category";
-
-    @include breakpoint(extra-large) {
-      grid-template-areas:
-        ". . . . status"
-        "activity . . . ."
-        "excerpt excerpt excerpt likes-replies category";
+  &:hover {
+    .discourse-no-touch & {
+      border-color: var(--accent-color);
+      background: var(--d-content-background);
     }
+  }
 
-    @include breakpoint(mobile-extra-large) {
-      grid-template-rows: auto auto auto;
-      grid-template-areas:
-        "category category category category status"
-        ". . . . ."
-        "activity . . . likes-replies";
+  &.selected {
+    box-shadow:
+      0 0 0 2px var(--accent-color),
+      0 0 12px 1px var(--topic-card-shadow);
+  }
 
+  &.excerpt-expanded {
+    @include viewport.until(sm) {
       .topic-excerpt,
       .link-bottom-line {
         display: none;
       }
     }
 
-    .topic-likes-replies-data {
-      align-self: flex-end;
+    @include viewport.from(sm) {
+      grid-template-areas:
+        "creator title title status"
+        "creator category activity likes-replies "
+        "creator excerpt excerpt excerpt";
+
+      .bulk-select-enabled & {
+        grid-template-areas:
+          "bulk-select creator title title status"
+          "bulk-select creator category activity likes-replies "
+          " bulk-select creator excerpt excerpt excerpt";
+      }
     }
 
-    .topic-category-data {
-      align-items: flex-end;
+    // when there is enough space, excerpt can be next to likes-replies
+    @include viewport.from(lg) {
+      grid-template-areas:
+        "creator title title status"
+        "creator category activity ."
+        "creator excerpt excerpt likes-replies";
     }
+  }
 
-    .badge-category__wrapper {
-      height: min-content;
-    }
+  .link-top-line {
+    grid-area: title;
+    font-weight: 500;
+    display: flex;
+    align-items: center;
 
-    .link-bottom-line {
-      display: flex;
+    .title {
+      padding: 0;
     }
   }
 
@@ -126,7 +125,8 @@
   td.posters,
   td.posts,
   td.views,
-  td.activity {
+  td.activity,
+  td.topic-category-status-data {
     display: contents;
   }
 
@@ -134,59 +134,102 @@
     padding: 0;
   }
 
-  // topic activity, avatar, text
+  // display:nones
+  td.main-link a.topic-status,
+  .link-bottom-line,
+  .badge-notification.new-topic::before {
+    display: none;
+  }
+
+  .topic-category-data {
+    grid-area: category;
+    display: flex;
+  }
+
+  .badge-category__wrapper {
+    border-radius: var(--d-border-radius);
+    padding: 0.25em 0.5rem;
+    background-color: light-dark(
+      oklch(from var(--category-badge-color) 97% calc(c * 0.3) h),
+      oklch(from var(--category-badge-color) 45% calc(c * 0.5) h)
+    );
+
+    @include viewport.until(md) {
+      padding: 0.25em 0.5rem;
+      font-size: var(--font-down-2);
+    }
+
+    .badge-category__name {
+      color: light-dark(
+        oklch(from var(--category-badge-color) 20% calc(c * 1) h),
+        oklch(from var(--category-badge-color) 100% calc(c * 0.9) h)
+      );
+    }
+  }
+
+  // OP avatar
+  .topic-creator-data {
+    grid-area: creator;
+
+    .avatar {
+      height: 50px;
+      width: 50px;
+      border-radius: var(--d-border-radius);
+
+      @include viewport.until(sm) {
+        height: 30px;
+        width: 30px;
+        border-radius: 0.25rem;
+      }
+    }
+  }
+
+  .dot-separator {
+    width: 0.25em;
+    height: 0.25em;
+    background-color: var(--primary-500);
+    border-radius: 100%;
+    margin-inline: 0.25em;
+  }
+
+  // topic activity, icon, text
   .topic-activity-data {
+    @include ellipsis;
     grid-area: activity;
   }
 
   .topic-activity {
-    display: grid;
-    grid-template-columns: 20px auto auto auto;
+    display: flex;
     font-size: var(--font-down-1);
     height: 100%;
     align-items: center;
     gap: 0.25em;
   }
 
-  .topic-activity__user .avatar {
-    width: 20px;
-    height: 20px;
-    border-radius: 4px;
-  }
-
-  .topic-activity__user {
-    height: 20px;
-    width: 20px;
-    border-radius: 4px;
+  .topic-activity__type {
+    border-radius: 0.25rem;
     display: flex;
     align-items: center;
     justify-content: center;
-    background-color: var(--primary-low);
   }
 
   .topic-activity__username {
+    @include ellipsis;
     margin-left: 0.25em;
-    text-wrap: nowrap;
   }
 
-  @include breakpoint(mobile-extra-large) {
-    .topic-activity__username {
-      display: none;
-    }
-
-    .topic-activity__reason {
-      margin-left: 0.25em;
-    }
-  }
-
-  .topic-activity.--updated .topic-activity__reason {
-    margin-left: 0.25em;
+  // timestamp
+  td.activity .post-activity {
+    grid-area: activity;
+    font-size: var(--font-down-1);
+    color: var(--primary-500);
+    margin-left: auto;
+    padding: 0;
   }
 
   // status
   .topic-status-data {
     grid-area: status;
-    position: relative;
   }
 
   .topic-status-card {
@@ -194,23 +237,30 @@
     margin-left: auto;
     display: flex;
     flex-direction: row;
-    gap: 4px;
+    gap: 0.25em;
     align-items: center;
-    padding: 0 6px;
-    font-size: var(--font-down-2);
+    padding: 0.2em 0.5rem;
+    font-size: var(--font-down-3);
     font-weight: 600;
     border-radius: var(--d-border-radius);
     border: 1px solid var(--status-color);
     color: var(--status-color);
     width: min-content;
 
-    @include breakpoint("large", min-width) {
+    &.--pinned {
+      --status-color: var(--primary-500);
+    }
+
+    &.--hot {
+      --status-color: #e45735;
+    }
+
+    @include viewport.from(lg) {
       position: absolute;
-      right: 0;
-      top: -20px;
+      right: 1rem;
+      top: 0;
+      transform: translateY(-45%);
       background-color: var(--d-content-background);
-      height: 20px;
-      font-size: var(--font-down-3);
     }
 
     svg {
@@ -219,31 +269,15 @@
     }
   }
 
-  .topic-status-card.--pinned {
-    --status-color: var(--primary-500);
-  }
-
-  .topic-status-card.--hot {
-    --status-color: #e45735;
-  }
-
   .link-top-line .event-date {
     margin-left: 0.5em;
     font-size: var(--font-down-3);
   }
 
-  td.main-link a.topic-status {
-    display: none;
-  }
-
   .topic-list-data {
     padding: 0;
   }
 
-  td.main-link .link-top-line a.raw-topic-link {
-    padding: 0;
-  }
-
   .topic-post-badges .badge-notification.unread-posts,
   .topic-post-badges .badge-notification.new-topic {
     background-color: var(--tertiary);
@@ -256,31 +290,13 @@
     min-width: unset;
   }
 
-  .badge-notification.new-topic::before {
-    display: none;
-  }
-
-  // timestamp
-  td.activity .post-activity {
-    grid-area: activity;
-    font-size: var(--font-down-1);
-    color: var(--primary-500);
-    margin-left: auto;
-    padding: 0;
-  }
-
-  .link-bottom-line {
-    display: none;
-  }
-
-  // metadata
   // metadata - excerpt
-  .topic-excerpt,
-  td.main-link .link-bottom-line {
-    grid-row: 3 / -1;
-    grid-column: 1 / -3;
+  .topic-excerpt {
+    grid-area: excerpt;
     margin: 0;
+    padding: 0;
     font-size: var(--font-down-2);
+    width: 100%;
 
     .excerpt__contents {
       color: var(--primary-high);
@@ -292,42 +308,6 @@
     }
   }
 
-  td.topic-category-status-data {
-    display: contents;
-  }
-
-  td.topic-category-data {
-    grid-area: category;
-    display: flex;
-    justify-content: flex-end;
-
-    @include breakpoint(mobile-extra-large) {
-      justify-content: flex-start;
-    }
-  }
-
-  td.topic-category-data .badge-category__wrapper,
-  td.main-link .link-bottom-line .badge-category__wrapper {
-    border-radius: var(--d-border-radius);
-    padding: 3px 6px;
-    background-color: light-dark(
-      oklch(from var(--category-badge-color) 97% calc(c * 0.3) h),
-      oklch(from var(--category-badge-color) 45% calc(c * 0.5) h)
-    );
-
-    @include breakpoint(tablet) {
-      padding: 2px 6px;
-      font-size: var(--font-down-2);
-    }
-
-    .badge-category__name {
-      color: light-dark(
-        oklch(from var(--category-badge-color) 20% calc(c * 1) h),
-        oklch(from var(--category-badge-color) 100% calc(c * 0.9) h)
-      );
-    }
-  }
-
   td.main-link .discourse-tags {
     display: none;
   }
@@ -356,28 +336,31 @@
     gap: 0.5em;
     align-items: center;
     color: var(--primary-500);
+    font-size: var(--font-down-1-rem);
 
     svg {
       color: var(--primary-600);
     }
   }
-}
 
-.topic-list-item {
-  background: var(--d-content-background);
-  box-shadow: 0 0 12px 1px var(--topic-card-shadow);
+  .bulk-select {
+    grid-area: bulk-select;
+    padding: 0;
+    margin: 0;
+    align-self: center;
+    justify-self: center;
 
-  &:hover {
-    .discourse-no-touch & {
-      border-color: var(--accent-color);
-      background: var(--d-content-background);
+    @include viewport.until(sm) {
+      align-self: flex-start;
     }
-  }
 
-  &.selected {
-    box-shadow:
-      0 0 0 2px var(--accent-color),
-      0 0 12px 1px var(--topic-card-shadow);
+    label {
+      margin: 0;
+    }
+
+    &th {
+      display: none;
+    }
   }
 }
 
@@ -393,7 +376,7 @@
     ". . . . . . dropdown"
     "avatar update metadata metadata metadata . category";
 
-  @include breakpoint(mobile-extra-large) {
+  @include viewport.until(sm) {
     grid-template-columns: min-content min-content auto min-content min-content min-content min-content;
     grid-template-areas:
       " . . . . . . dropdown"
@@ -407,7 +390,7 @@
   &.has-metadata {
     grid-template-columns: 20px min-content min-content auto min-content min-content min-content;
 
-    @include breakpoint(mobile-extra-large) {
+    @include viewport.until(sm) {
       grid-template-areas:
         ". . . . . . . dropdown"
         "update update metadata metadata metadata metadata category category";
@@ -427,11 +410,11 @@
       "excerpt excerpt excerpt ."
       "excerpt excerpt excerpt category";
 
-    @include breakpoint(extra-large, $rule: min-width) {
+    @include viewport.from(xl) {
       grid-template-columns: 20px min-content auto min-content;
     }
 
-    @include breakpoint(mobile-extra-large) {
+    @include viewport.until(sm) {
       grid-template-columns: auto min-content;
       grid-template-areas:
         ".  dropdown"
@@ -451,7 +434,7 @@
         "excerpt excerpt excerpt . "
         "excerpt excerpt excerpt category";
 
-      @include breakpoint(mobile-extra-large) {
+      @include viewport.until(sm) {
         grid-template-columns: auto min-content;
         grid-template-areas:
           " . dropdown"
@@ -561,7 +544,7 @@
     ". . . . . status dropdown"
     "activity . . . . likes-replies category";
 
-  @include breakpoint(mobile-extra-large) {
+  @include viewport.until(sm) {
     grid-template-columns: 20px min-content min-content auto min-content min-content min-content 36px;
     grid-template-areas:
       "category category . . . . status dropdown"
@@ -619,19 +602,25 @@ body.user-messages-page {
     grid-template-rows: auto auto;
 
     &:hover {
-      background-color: var(--primary-low);
-      border-color: var(--primary-200);
+      .discourse-no-touch & {
+        background-color: var(--primary-low);
+        border-color: var(--primary-200);
+      }
     }
 
     td.topic-category-data,
     td.topic-likes-replies-data,
-    td.topic-status-data {
+    td.topic-status-data,
+    td.topic-creator-data {
       display: none;
     }
 
+    .main-link .link-top-line {
+      grid-area: title;
+    }
+
     &.visited .main-link .link-top-line {
       font-weight: normal;
-      grid-area: title;
     }
 
     td.topic-activity-data {
@@ -658,73 +647,6 @@ body.user-messages-page {
   }
 }
 
-// Bulk select
-.bulk-select-enabled .topic-list-body .topic-list-item {
-  grid-template-areas:
-    "bulk-select . . . status"
-    "bulk-select activity activity . category";
-
-  @include breakpoint(large) {
-    grid-template-areas:
-      "bulk-select . . . status"
-      "bulk-select activity activity . category";
-  }
-
-  @include breakpoint(mobile-extra-large) {
-    grid-template-areas:
-      "bulk-select category . . .  status"
-      "bulk-select . . . . ."
-      "bulk-select activity activity . . .";
-
-    td.main-link .link-top-line,
-    &.--has-status-card td.main-link .link-top-line {
-      grid-column: 2/-1;
-      grid-row: 2;
-      font-weight: 500;
-    }
-  }
-
-  td.topic-likes-replies-data {
-    display: none;
-  }
-
-  td.main-link .link-top-line,
-  &.--has-status-card td.main-link .link-top-line {
-    grid-column: 2/-1;
-    font-weight: 500;
-  }
-
-  .topic-excerpt {
-    grid-area: excerpt;
-    margin: 0;
-  }
-
-  &.excerpt-expanded {
-    grid-template-areas:
-      "bulk-select . . . status" "bulk-select activity . . ."
-      "bulk-select excerpt excerpt excerpt category";
-
-    @include breakpoint(mobile-extra-large) {
-      grid-template-areas:
-        "bulk-select category . . .  status"
-        "bulk-select . . . . ."
-        "bulk-select activity activity . . .";
-    }
-  }
-
-  .bulk-select {
-    grid-area: bulk-select;
-    padding: 0;
-    margin: 0;
-    align-self: center;
-    justify-self: center;
-
-    label {
-      margin: 0;
-    }
-  }
-}
-
 .event-date-container {
   display: inline-flex;
   position: relative;

scss/topic.scss

@@ -1,3 +1,5 @@
+@use "lib/viewport";
+
 .post-stream {
   .contents {
     font-size: var(--font-up-1);
@@ -6,14 +8,6 @@
   }
 }
 
-.container.posts .topic-navigation:not(.with-topic-progress) {
-  // super fragile because new sticky topic title doesn't have a calculated value (= 53px with this font and size but…)
-  top: calc(
-    var(--header-offset, 60px) + 53px + calc(var(--spacing-block-l) * 2)
-  );
-  z-index: 300;
-}
-
 .timeline-container .topic-timeline {
   min-width: unset; // why we have this?
 
@@ -21,7 +15,7 @@
     border-left: 1px solid var(--accent-color);
 
     .timeline-scroller {
-      @include breakpoint("medium", $rule: min-width) {
+      @include viewport.from(lg) {
         margin-left: -4.5px;
         background: var(--d-content-background);
         height: 40px !important; // height is coming from element style have no other choice
@@ -36,7 +30,7 @@
     .timeline-handle {
       background-color: var(--accent-color);
 
-      @include breakpoint("medium", $rule: min-width) {
+      @include viewport.from(lg) {
         width: 8px;
         border-radius: 10px;
         height: calc(100% - 6px);
@@ -47,7 +41,7 @@
 
 // should probably get rid of this extra specificity class in core?
 .timeline-container.timeline-fullscreen {
-  @include breakpoint("medium", $rule: max-width) {
+  @include viewport.until(lg) {
     .topic-timeline
       .timeline-scrollarea
       .timeline-scroller
@@ -60,7 +54,7 @@
 .container.posts {
   grid-template-columns: auto 8em;
 
-  @media screen and (max-width: 924px) {
+  @media screen and (width <= 924px) {
     grid-template-columns: auto auto;
   }
 

scss/welcome-banner.scss

@@ -1,3 +1,5 @@
+@use "lib/viewport";
+
 .welcome-banner {
   &__wrap {
     display: grid;
@@ -9,11 +11,11 @@
     padding: 1.5em 0 2.5em;
     margin-bottom: 0;
 
-    @media screen and (max-width: 768px) {
+    @media screen and (width <= 768px) {
       padding: 1em;
     }
 
-    @include breakpoint("mobile-extra-large") {
+    @include viewport.until(sm) {
       display: block;
       padding: 0.5em;
       margin-top: 0;
@@ -25,22 +27,22 @@
       width: 100%;
       align-self: center;
 
-      @media screen and (max-width: 1028px) {
+      @media screen and (width <= 1028px) {
         grid-row: 2/-1;
         grid-column: 1/-1;
       }
 
-      @media screen and (max-width: 768px) {
+      @media screen and (width <= 768px) {
         grid-column: 2/-1;
         grid-row: 1/-1;
       }
 
-      @media screen and (max-width: 600px) {
+      @media screen and (width <= 600px) {
         grid-row: 2/-1;
         grid-column: 1/-1;
       }
 
-      @include breakpoint("mobile-extra-large") {
+      @include viewport.until(sm) {
         display: none;
       }
     }
@@ -54,7 +56,7 @@
   .search-menu-container .search-input {
     background: var(--d-content-background);
     border: 1px solid var(--search-color);
-    box-shadow: 0 4px 10px rgba(52, 6, 121, 15%);
+    box-shadow: 0 4px 10px rgb(52, 6, 121, 15%);
   }
 
   .search-menu .search-input:focus-within,
@@ -86,7 +88,7 @@
     font-weight: 400;
     color: var(--search-color);
 
-    @media screen and (max-width: 1028px) {
+    @media screen and (width <= 1028px) {
       font-size: var(--font-up-4);
       grid-column: 1/-1;
       grid-row: 1;
@@ -94,21 +96,21 @@
       margin-bottom: 0.5em;
     }
 
-    @media screen and (max-width: 768px) {
+    @media screen and (width <= 768px) {
       text-align: left;
       grid-column: 1/2;
       grid-row: 1/-1;
       font-size: var(--font-up-3);
     }
 
-    @media screen and (max-width: 600px) {
+    @media screen and (width <= 600px) {
       grid-column: 1/-1;
       grid-row: 1;
       text-align: center;
       margin-bottom: 0.5em;
     }
 
-    @include breakpoint("mobile-extra-large") {
+    @include viewport.until(sm) {
       font-size: var(--font-up-2);
     }
   }

spec/system/horizon_high_level_spec.rb

@@ -39,6 +39,7 @@ describe "Horizon theme | High level", type: :system do
         "topic-status-data",
         "topic-category-data",
         "topic-likes-replies-data",
+        "topic-creator-data",
         "topic-activity-data",
       ],
     )