diff --git a/src/components/instance-tab.tsx b/src/components/instance-tab.tsx
index 2da6a1f6..5c4e821b 100644
--- a/src/components/instance-tab.tsx
+++ b/src/components/instance-tab.tsx
@@ -27,24 +27,20 @@ function formatFolderName(path: string, instances: Instance[], currentInstance:
 
 const InstanceTab: Component<InstanceTabProps> = (props) => {
   return (
-    <div class="instance-tab-container group">
+    <div class="group">
       <button
-        class={`instance-tab inline-flex items-center gap-2 px-3 py-2 rounded-t-md max-w-[200px] transition-colors ${
-          props.active
-            ? "bg-blue-500 text-white"
-            : "bg-gray-100 dark:bg-gray-800 text-gray-700 dark:text-gray-300 hover:bg-gray-200 dark:hover:bg-gray-700"
-        }`}
+        class={`tab-base ${props.active ? "tab-active" : "tab-inactive"}`}
         onClick={props.onSelect}
         title={props.instance.folder}
         role="tab"
         aria-selected={props.active}
       >
         <FolderOpen class="w-4 h-4 flex-shrink-0" />
-        <span class="tab-label truncate text-sm">
+        <span class="tab-label">
           {props.instance.folder.split("/").pop() || props.instance.folder}
         </span>
         <span
-          class="tab-close opacity-0 group-hover:opacity-100 hover:bg-red-500 dark:hover:bg-red-600 hover:text-white rounded p-0.5 transition-opacity ml-auto cursor-pointer"
+          class="tab-close ml-auto"
           onClick={(e) => {
             e.stopPropagation()
             props.onClose()
diff --git a/src/components/instance-tabs.tsx b/src/components/instance-tabs.tsx
index 79efee29..4fe8c7a1 100644
--- a/src/components/instance-tabs.tsx
+++ b/src/components/instance-tabs.tsx
@@ -15,8 +15,8 @@ interface InstanceTabsProps {
 
 const InstanceTabs: Component<InstanceTabsProps> = (props) => {
   return (
-    <div class="instance-tabs bg-gray-50 dark:bg-gray-900 border-b border-gray-200 dark:border-gray-700">
-      <div class="tabs-container flex items-center justify-between gap-1 px-2 py-1 overflow-x-auto" role="tablist">
+    <div class="tab-bar tab-bar-instance">
+      <div class="tab-container" role="tablist">
         <div class="flex items-center gap-1 overflow-x-auto">
           <For each={Array.from(props.instances.entries())}>
             {([id, instance]) => (
@@ -29,7 +29,7 @@ const InstanceTabs: Component<InstanceTabsProps> = (props) => {
             )}
           </For>
           <button
-            class="new-tab-button inline-flex items-center justify-center w-8 h-8 rounded-md text-gray-600 dark:text-gray-300 hover:bg-gray-200 dark:hover:bg-gray-800 transition-colors"
+            class="new-tab-button"
             onClick={props.onNew}
             title="New instance (Cmd/Ctrl+N)"
             aria-label="New instance"
diff --git a/src/components/session-tab.tsx b/src/components/session-tab.tsx
index 42fdb0cd..8ee0e54b 100644
--- a/src/components/session-tab.tsx
+++ b/src/components/session-tab.tsx
@@ -18,13 +18,13 @@ const SessionTab: Component<SessionTabProps> = (props) => {
   }
 
   return (
-    <div class="session-tab-container group">
+    <div class="group">
       <button
-        class={`session-tab inline-flex items-center gap-2 px-3 py-1.5 rounded-t-md max-w-[150px] transition-colors text-sm ${
+        class={`session-tab-base ${
           props.active
-            ? "bg-white dark:bg-gray-800 border-b-2 border-blue-500 font-medium text-gray-900 dark:text-gray-100"
-            : "text-gray-600 dark:text-gray-400 hover:bg-gray-100 dark:hover:bg-gray-700"
-        } ${props.special === "info" ? "text-gray-500 dark:text-gray-400" : ""} ${props.isParent && !props.active ? "font-semibold" : ""}`}
+            ? "session-tab-active"
+            : "session-tab-inactive"
+        } ${props.special === "info" ? "session-tab-special" : ""} ${props.isParent && !props.active ? "font-semibold" : ""}`}
         onClick={props.onSelect}
         title={label()}
         role="tab"
@@ -33,10 +33,10 @@ const SessionTab: Component<SessionTabProps> = (props) => {
         <Show when={props.special === "info"} fallback={<MessageSquare class="w-3.5 h-3.5 flex-shrink-0" />}>
           <Info class="w-3.5 h-3.5 flex-shrink-0" />
         </Show>
-        <span class="tab-label truncate">{label()}</span>
+        <span class="tab-label">{label()}</span>
         <Show when={!props.special && props.onClose}>
           <span
-            class="tab-close opacity-0 group-hover:opacity-100 hover:bg-red-500 hover:text-white rounded p-0.5 transition-opacity cursor-pointer"
+            class="tab-close"
             onClick={(e) => {
               e.stopPropagation()
               props.onClose?.()
diff --git a/src/components/session-tabs.tsx b/src/components/session-tabs.tsx
index aaa25114..fca7c0ea 100644
--- a/src/components/session-tabs.tsx
+++ b/src/components/session-tabs.tsx
@@ -19,8 +19,8 @@ const SessionTabs: Component<SessionTabsProps> = (props) => {
   const totalTabs = () => sessionsList().length + 1
 
   return (
-    <div class="session-tabs bg-white dark:bg-gray-900 border-b border-gray-200 dark:border-gray-700">
-      <div class="tabs-container flex items-center justify-between gap-1 px-2 py-1 overflow-x-auto" role="tablist">
+    <div class="tab-bar tab-bar-session">
+      <div class="tab-container" role="tablist">
         <div class="flex items-center gap-1 overflow-x-auto">
           <For each={sessionsList()}>
             {([id, session]) => (
@@ -39,7 +39,7 @@ const SessionTabs: Component<SessionTabsProps> = (props) => {
             onSelect={() => props.onSelect("info")}
           />
           <button
-            class="new-tab-button inline-flex items-center justify-center w-8 h-8 rounded-md text-gray-600 dark:text-gray-300 hover:bg-gray-100 dark:hover:bg-gray-800 transition-colors"
+            class="new-tab-button"
             onClick={props.onNew}
             title="New parent session (Cmd/Ctrl+T)"
             aria-label="New parent session"
diff --git a/src/styles/components.css b/src/styles/components.css
index 6f277aa0..7e3d17d7 100644
--- a/src/styles/components.css
+++ b/src/styles/components.css
@@ -152,4 +152,127 @@
 
 [data-theme="dark"] .attachment-remove:hover {
   background-color: rgba(0, 128, 255, 0.2);
+}
+
+/* Tab component utilities */
+.tab-bar {
+  @apply border-b;
+  border-color: var(--border-base);
+}
+
+.tab-bar-instance {
+  background-color: var(--surface-secondary);
+}
+
+.tab-bar-session {
+  background-color: var(--surface-base);
+}
+
+[data-theme="dark"] .tab-bar-session {
+  background-color: var(--surface-secondary);
+}
+
+.tab-container {
+  @apply flex items-center justify-between gap-1 px-2 py-1 overflow-x-auto;
+}
+
+.tab-base {
+  @apply inline-flex items-center gap-2 px-3 py-2 rounded-t-md max-w-[200px] transition-colors text-sm font-medium;
+  font-family: var(--font-family-sans);
+  outline: none;
+}
+
+.tab-base:focus-visible {
+  @apply ring-2 ring-offset-1;
+  ring-color: var(--accent-primary);
+  ring-offset-color: var(--surface-base);
+}
+
+.tab-active {
+  background-color: var(--accent-primary);
+  color: var(--text-inverted);
+}
+
+.tab-inactive {
+  background-color: var(--surface-secondary);
+  color: var(--text-secondary);
+}
+
+.tab-inactive:hover {
+  background-color: var(--surface-hover);
+}
+
+[data-theme="dark"] .tab-inactive {
+  background-color: var(--surface-muted);
+}
+
+[data-theme="dark"] .tab-inactive:hover {
+  background-color: var(--surface-hover);
+}
+
+.tab-label {
+  @apply truncate;
+}
+
+.tab-close {
+  @apply opacity-0 group-hover:opacity-100 hover:bg-red-500 hover:text-white rounded p-0.5 transition-all cursor-pointer;
+}
+
+.tab-close:focus-visible {
+  @apply ring-2 ring-offset-1;
+  ring-color: var(--accent-primary);
+  ring-offset-color: inherit;
+}
+
+.new-tab-button {
+  @apply inline-flex items-center justify-center w-8 h-8 rounded-md transition-colors;
+  background-color: var(--surface-secondary);
+  color: var(--text-muted);
+}
+
+.new-tab-button:hover {
+  background-color: var(--surface-hover);
+}
+
+.new-tab-button:focus-visible {
+  @apply ring-2 ring-offset-1;
+  ring-color: var(--accent-primary);
+  ring-offset-color: var(--surface-base);
+}
+
+/* Session tab specific styles */
+.session-tab-base {
+  @apply inline-flex items-center gap-2 px-3 py-1.5 rounded-t-md max-w-[150px] transition-colors text-sm;
+  font-family: var(--font-family-sans);
+  outline: none;
+  border-bottom: 2px solid transparent;
+}
+
+.session-tab-base:focus-visible {
+  @apply ring-2 ring-offset-1;
+  ring-color: var(--accent-primary);
+  ring-offset-color: var(--surface-base);
+}
+
+.session-tab-active {
+  background-color: var(--surface-base);
+  border-bottom-color: var(--accent-primary);
+  color: var(--text-primary);
+  font-weight: var(--font-weight-medium);
+}
+
+[data-theme="dark"] .session-tab-active {
+  background-color: var(--surface-muted);
+}
+
+.session-tab-inactive {
+  color: var(--text-muted);
+}
+
+.session-tab-inactive:hover {
+  background-color: var(--surface-hover);
+}
+
+.session-tab-special {
+  color: var(--text-muted);
 }
\ No newline at end of file