diff --git a/src/lib/components/SphereBar.svelte b/src/lib/components/SphereBar.svelte
index a8060a6..272e2bd 100644
--- a/src/lib/components/SphereBar.svelte
+++ b/src/lib/components/SphereBar.svelte
@@ -1,16 +1,19 @@
 <script lang="ts">
   import { slide, type SlideParams } from 'svelte/transition';
+  import { page } from '$app/stores';
   import state from '$lib/ws';
+  import userConfig from '$lib/user_config';
   import userData from '$lib/user_data';
   import type { Sphere } from '$lib/types/sphere';
-  import { page } from '$app/stores';
-  import { SphereChannelType } from '$lib/types/channel';
+  import type { Category } from '$lib/types/category';
+  import { SphereChannelType, type Channel } from '$lib/types/channel';
 
   let currentSphere: Sphere | null = null;
+  let currentChannel: Channel | null = null;
 
   let spheres: Sphere[] = Object.values($state.spheres ?? []);
   $: {
-    let currentChannel = $state.channels[Number.parseInt($page.params.channel_id)];
+    currentChannel = $state.channels[Number.parseInt($page.params.channel_id)];
     if (
       currentChannel &&
       (currentChannel.type == SphereChannelType.TEXT ||
@@ -29,6 +32,21 @@
     if (window.screen.width > 1000) return { duration: 0 };
     return slide(node, params);
   };
+
+  const toggleCategory = (e: Event, c: Category) => {
+    if ((e as ToggleEvent).newState == 'closed') {
+      if ($userConfig.hiddenCategories) {
+        $userConfig.hiddenCategories?.push(c.id);
+      } else {
+        $userConfig.hiddenCategories = [c.id];
+      }
+    } else {
+      let index = $userConfig.hiddenCategories?.indexOf(c.id) ?? -1;
+      if (index >= 0) $userConfig.hiddenCategories!.splice(index, 1);
+    }
+
+    $userConfig = $userConfig;
+  };
 </script>
 
 <div id="sphere-bar" style:width={currentSphere ? '300px' : 'auto'}>
@@ -60,17 +78,32 @@
       <h3 id="sphere-name">{currentSphere.name ?? currentSphere.slug}</h3>
       <hr />
       <ul id="sphere-channel-list">
-        {#each currentSphere.categories as category (category.id)}
-          {#if category.id != currentSphere.id}
-            <h4 class="category">
-              > {category.name}
-            </h4>
-          {/if}
-          {#each category.channels as channel (channel.id)}
-            <a href="/channels/{channel.id}" class="channel">
-              # {channel.name}
-            </a>
-          {/each}
+        {#each currentSphere.categories[0].channels as channel (channel.id)}
+          <a
+            href="/channels/{channel.id}"
+            class={`channel${channel == currentChannel ? ' current' : ''}`}
+          >
+            # {channel.name}
+          </a>
+        {/each}
+        {#each currentSphere.categories.slice(1) as category (category.id)}
+          <details
+            class="category"
+            open={!$userConfig.hiddenCategories?.includes(category.id)}
+            on:toggle={(e) => toggleCategory(e, category)}
+          >
+            <summary class="category-name">{category.name}</summary>
+            {#if !category.collapsed}
+              {#each category.channels as channel (channel.id)}
+                <a
+                  href="/channels/{channel.id}"
+                  class={`channel${channel == currentChannel ? ' current' : ''}`}
+                >
+                  # {channel.name}
+                </a>
+              {/each}
+            {/if}
+          </details>
         {/each}
       </ul>
     </div>
@@ -135,13 +168,43 @@
 
   .category {
     margin: 10px 0;
+    user-select: none;
+    display: flex;
+    flex-direction: column;
+  }
+
+  .category summary {
+    margin: 0;
+  }
+
+  .category-name {
+    color: var(--color-text);
+    cursor: pointer;
+    padding: 5px;
+    border-radius: 5px;
+  }
+
+  .category-name:hover {
+    background-color: var(--purple-300);
   }
 
   .channel {
-    padding-left: 5px;
+    padding: 5px;
+    margin: 2px;
+    border-radius: 5px;
     text-decoration: none;
   }
 
+  .channel:hover {
+    color: var(--gray-600);
+    background-color: var(--purple-300);
+  }
+
+  .channel.current {
+    color: var(--gray-600);
+    background-color: var(--purple-400);
+  }
+
   #sphere-banner {
     width: 100%;
     height: 115px;
diff --git a/src/lib/types/category.ts b/src/lib/types/category.ts
index 3e04bea..fafa051 100644
--- a/src/lib/types/category.ts
+++ b/src/lib/types/category.ts
@@ -1,8 +1,9 @@
-import { SphereChannel } from "./channel";
+import type { SphereChannel } from './channel';
 
 export interface Category {
-    id: number;
-    name: string;
-    channels: SphereChannel[];
-    position: number;
-}
\ No newline at end of file
+  id: number;
+  name: string;
+  channels: SphereChannel[];
+  position: number;
+  collapsed: boolean;
+}
diff --git a/src/lib/types/ui/config.ts b/src/lib/types/ui/config.ts
index af50716..725ee15 100644
--- a/src/lib/types/ui/config.ts
+++ b/src/lib/types/ui/config.ts
@@ -5,4 +5,5 @@ export interface UserConfig {
   userList?: boolean;
   recentEmojis?: string[];
   lastChannel?: number;
+  hiddenCategories?: number[];
 }
diff --git a/src/lib/ws.ts b/src/lib/ws.ts
index 304ca73..1e89841 100644
--- a/src/lib/ws.ts
+++ b/src/lib/ws.ts
@@ -15,13 +15,13 @@ const state = writable<State>({
   users: [],
   spheres: [],
   categories: [],
-  channels: [],
+  channels: []
 });
 
 let ws: WebSocket | null = null;
 let pingInterval: NodeJS.Timeout | null = null;
 let lastAuthorID: { [name: number]: number } = {};
-let lastAuthorData: { [name: number]: { name: string, avatar: string | number | undefined } } = {};
+let lastAuthorData: { [name: number]: { name: string; avatar: string | number | undefined } } = {};
 let notification: Notification;
 let notification_opt: number;
 let connected = false;
@@ -76,15 +76,13 @@ const connect = async (userData: UserData) => {
             u.members.forEach((m) => {
               state.users[m.user.id] = m.user;
             });
-            // u.channels.forEach((c) => {
-            //   state.channels[c.id] = c;
-            // });
             u.categories.forEach((c) => {
+              c.collapsed = false; // TODO: Maybe remember this between sessions?
               state.categories[c.id] = c;
               c.channels.forEach((c) => {
                 state.channels[c.id] = c;
-              })
-            })
+              });
+            });
             state.spheres[u.id] = u;
           });
           state.users[payload.d.user.id] = payload.d.user;
@@ -140,27 +138,32 @@ const connect = async (userData: UserData) => {
           const authorData = {
             name:
               payload.d._disguise?.name ??
-              payload.d.author.display_name ?? payload.d.author.username,
-            avatar:
-              payload.d._disguise?.avatar ??
-              payload.d.author.avatar
+              payload.d.author.display_name ??
+              payload.d.author.username,
+            avatar: payload.d._disguise?.avatar ?? payload.d.author.avatar
           };
           if (!lastAuthorData[channelID]) {
             let lastMessage = get(state).messages[channelID].messages.at(-1);
             if (lastMessage) {
               lastAuthorData[channelID] = {
-                name: lastMessage?._disguise?.name ??
-                  lastMessage.author.display_name ?? lastMessage.author.username,
+                name:
+                  lastMessage?._disguise?.name ??
+                  lastMessage.author.display_name ??
+                  lastMessage.author.username,
                 avatar: lastMessage?._disguise?.avatar ?? lastMessage?.author.avatar
               };
               lastAuthorID[channelID] = lastMessage?.author.id;
             }
           }
-          let sameData = authorData?.name == lastAuthorData[channelID]?.name && authorData?.avatar == lastAuthorData[channelID].avatar;
+          let sameData =
+            authorData?.name == lastAuthorData[channelID]?.name &&
+            authorData?.avatar == lastAuthorData[channelID].avatar;
           const message = {
             renderedContent: content,
             showAuthor: !sameData || payload.d.author.id != lastAuthorID[channelID],
-            mentioned: new RegExp(`(?<!\\\\)<@${userData.user.id}>`, 'gm').test(payload.d.content ?? ''),
+            mentioned: new RegExp(`(?<!\\\\)<@${userData.user.id}>`, 'gm').test(
+              payload.d.content ?? ''
+            ),
             ...payload.d
           };
           lastAuthorData[channelID] = authorData;
@@ -190,7 +193,7 @@ const connect = async (userData: UserData) => {
                 }
               );
               // new Audio('...').play();
-            };
+            }
           }
           state.update((state) => {
             if (state.messages[message.channel.id]) {