diff --git a/.changeset/fix-sidebar-collapse-single-root.md b/.changeset/fix-sidebar-collapse-single-root.md
new file mode 100644
index 0000000000..52444cc399
--- /dev/null
+++ b/.changeset/fix-sidebar-collapse-single-root.md
@@ -0,0 +1,5 @@
+---
+"@moonshot-ai/kimi-code": patch
+---
+
+web: Fix the collapsed sidebar not hiding and squeezing the conversation layout.
diff --git a/apps/kimi-web/src/components/Sidebar.vue b/apps/kimi-web/src/components/Sidebar.vue
index 0a31ae5fc0..a3d09b8178 100644
--- a/apps/kimi-web/src/components/Sidebar.vue
+++ b/apps/kimi-web/src/components/Sidebar.vue
@@ -752,10 +752,13 @@ onBeforeUnmount(() => {
       @select="onSelectSession"
       @close="showSearch = false"
     />
+    <!-- Keep inside <aside>: a top-level <Teleport> makes Sidebar multi-root,
+         which breaks v-show on the host (Vue can't apply display:none to a
+         Fragment). Teleport still renders to body regardless of placement. -->
+    <Teleport to="body">
+      <DesignSystemView v-if="showDesignSystem" @close="showDesignSystem = false" />
+    </Teleport>
   </aside>
-  <Teleport to="body">
-    <DesignSystemView v-if="showDesignSystem" @close="showDesignSystem = false" />
-  </Teleport>
 </template>
 
 <style scoped>