diff --git a/ui/src/components/ui/tabs/Tabs.vue b/ui/src/components/ui/tabs/Tabs.vue
index 7505f12..69cb5aa 100644
--- a/ui/src/components/ui/tabs/Tabs.vue
+++ b/ui/src/components/ui/tabs/Tabs.vue
@@ -18,7 +18,7 @@ const forwarded = useForwardPropsEmits(delegatedProps, emits)
     data-slot="tabs"
     :data-orientation="forwarded.orientation || 'horizontal'"
     v-bind="forwarded"
-    :class="cn('gap-2 group/tabs flex data-horizontal:flex-col', props.class)"
+    :class="cn('gap-2 group/tabs flex data-[orientation=horizontal]:flex-col', props.class)"
   >
     <slot v-bind="slotProps" />
   </TabsRoot>
diff --git a/ui/src/components/ui/tabs/TabsTrigger.vue b/ui/src/components/ui/tabs/TabsTrigger.vue
index 2251c1c..1c3874b 100644
--- a/ui/src/components/ui/tabs/TabsTrigger.vue
+++ b/ui/src/components/ui/tabs/TabsTrigger.vue
@@ -16,10 +16,10 @@ const forwardedProps = useForwardProps(delegatedProps)
   <TabsTrigger
     data-slot="tabs-trigger"
     :class="cn(
-      'gap-1.5 rounded-md border border-transparent px-1.5 py-0.5 text-sm font-medium group-data-[variant=default]/tabs-list:data-active:shadow-sm group-data-[variant=line]/tabs-list:data-active:shadow-none [&_svg:not([class*=size-])]:size-4 has-data-[icon=inline-end]:pr-1 has-data-[icon=inline-start]:pl-1 relative inline-flex h-[calc(100%-1px)] flex-1 items-center justify-center whitespace-nowrap text-foreground/60 transition-all group-data-vertical/tabs:w-full group-data-vertical/tabs:justify-start hover:text-foreground focus-visible:border-ring focus-visible:ring-3 focus-visible:ring-ring/50 focus-visible:outline-1 focus-visible:outline-ring disabled:pointer-events-none disabled:opacity-50 dark:text-muted-foreground dark:hover:text-foreground [&_svg]:pointer-events-none [&_svg]:shrink-0',
+      'gap-1.5 rounded-md border border-transparent px-1.5 py-0.5 text-sm font-medium group-data-[variant=default]/tabs-list:data-active:shadow-sm group-data-[variant=line]/tabs-list:data-active:shadow-none [&_svg:not([class*=size-])]:size-4 has-data-[icon=inline-end]:pr-1 has-data-[icon=inline-start]:pl-1 relative inline-flex h-[calc(100%-1px)] flex-1 items-center justify-center whitespace-nowrap text-foreground/60 transition-all group-data-[orientation=vertical]/tabs:w-full group-data-[orientation=vertical]/tabs:justify-start hover:text-foreground focus-visible:border-ring focus-visible:ring-3 focus-visible:ring-ring/50 focus-visible:outline-1 focus-visible:outline-ring disabled:pointer-events-none disabled:opacity-50 dark:text-muted-foreground dark:hover:text-foreground [&_svg]:pointer-events-none [&_svg]:shrink-0',
       'group-data-[variant=line]/tabs-list:bg-transparent group-data-[variant=line]/tabs-list:data-active:bg-transparent dark:group-data-[variant=line]/tabs-list:data-active:border-transparent dark:group-data-[variant=line]/tabs-list:data-active:bg-transparent',
       'data-active:bg-background data-active:text-foreground dark:data-active:border-input dark:data-active:bg-input/30 dark:data-active:text-foreground',
-      'after:absolute after:bg-foreground after:opacity-0 after:transition-opacity group-data-horizontal/tabs:after:inset-x-0 group-data-horizontal/tabs:after:bottom-[-5px] group-data-horizontal/tabs:after:h-0.5 group-data-vertical/tabs:after:inset-y-0 group-data-vertical/tabs:after:-right-1 group-data-vertical/tabs:after:w-0.5 group-data-[variant=line]/tabs-list:data-active:after:opacity-100',
+      'after:absolute after:bg-foreground after:opacity-0 after:transition-opacity group-data-[orientation=horizontal]/tabs:after:inset-x-0 group-data-[orientation=horizontal]/tabs:after:bottom-[-5px] group-data-[orientation=horizontal]/tabs:after:h-0.5 group-data-[orientation=vertical]/tabs:after:inset-y-0 group-data-[orientation=vertical]/tabs:after:-right-1 group-data-[orientation=vertical]/tabs:after:w-0.5 group-data-[variant=line]/tabs-list:data-active:after:opacity-100',
       props.class,
     )"
     v-bind="forwardedProps"
diff --git a/ui/src/components/ui/tabs/index.ts b/ui/src/components/ui/tabs/index.ts
index 7311814..4f333b4 100644
--- a/ui/src/components/ui/tabs/index.ts
+++ b/ui/src/components/ui/tabs/index.ts
@@ -7,7 +7,7 @@ export { default as TabsList } from './TabsList.vue'
 export { default as TabsTrigger } from './TabsTrigger.vue'
 
 export const tabsListVariants = cva(
-  'rounded-lg p-0.75 group-data-horizontal/tabs:h-8 data-[variant=line]:rounded-none group/tabs-list inline-flex w-fit items-center justify-center text-muted-foreground group-data-vertical/tabs:h-fit group-data-vertical/tabs:flex-col',
+  'rounded-lg p-0.75 group-data-[orientation=horizontal]/tabs:h-8 data-[variant=line]:rounded-none group/tabs-list inline-flex w-fit items-center justify-center text-muted-foreground group-data-[orientation=vertical]/tabs:h-fit group-data-[orientation=vertical]/tabs:flex-col',
   {
     variants: {
       variant: {
diff --git a/ui/src/components/ui/tabs/tabs.test.ts b/ui/src/components/ui/tabs/tabs.test.ts
new file mode 100644
index 0000000..bb14ff3
--- /dev/null
+++ b/ui/src/components/ui/tabs/tabs.test.ts
@@ -0,0 +1,46 @@
+import { mount } from '@vue/test-utils'
+import { describe, expect, it } from 'vitest'
+import { defineComponent } from 'vue'
+import { tabsListVariants } from '.'
+import Tabs from './Tabs.vue'
+import TabsContent from './TabsContent.vue'
+import TabsList from './TabsList.vue'
+import TabsTrigger from './TabsTrigger.vue'
+
+describe('tabs orientation classes', () => {
+  it('matches data-orientation on the tabs group, not boolean data-horizontal', () => {
+    const classes = tabsListVariants()
+    expect(classes).toContain('group-data-[orientation=horizontal]/tabs:h-8')
+    expect(classes).toContain('group-data-[orientation=vertical]/tabs:h-fit')
+    expect(classes).toContain('group-data-[orientation=vertical]/tabs:flex-col')
+    expect(classes).not.toContain('group-data-horizontal/tabs:')
+    expect(classes).not.toContain('group-data-vertical/tabs:')
+  })
+
+  it('stacks the tab list above content for the default horizontal orientation', () => {
+    const Harness = defineComponent({
+      components: { Tabs, TabsList, TabsTrigger, TabsContent },
+      template: `
+        <Tabs default-value="a">
+          <TabsList>
+            <TabsTrigger value="a">A</TabsTrigger>
+          </TabsList>
+          <TabsContent value="a">panel</TabsContent>
+        </Tabs>
+      `
+    })
+    const wrapper = mount(Harness)
+    const root = wrapper.get('[data-slot="tabs"]')
+    expect(root.attributes('data-orientation')).toBe('horizontal')
+    expect(root.classes()).toContain('data-[orientation=horizontal]:flex-col')
+    expect(root.classes()).not.toContain('data-horizontal:flex-col')
+
+    const list = wrapper.get('[data-slot="tabs-list"]')
+    expect(list.classes()).toContain('group-data-[orientation=horizontal]/tabs:h-8')
+
+    const trigger = wrapper.get('[data-slot="tabs-trigger"]')
+    expect(trigger.classes()).toContain('group-data-[orientation=horizontal]/tabs:after:h-0.5')
+    expect(trigger.classes()).toContain('group-data-[orientation=vertical]/tabs:w-full')
+    expect(wrapper.text()).toContain('panel')
+  })
+})