diff --git a/src/app/chat/components/chat-screen.module.css b/src/app/chat/components/chat-screen.module.css
index 22cd59d2..c20e766e 100644
--- a/src/app/chat/components/chat-screen.module.css
+++ b/src/app/chat/components/chat-screen.module.css
@@ -1,6 +1,9 @@
 /* ChatScreen 编排层样式（仅 shell 容器 + 背景） */
 
 .shell {
+  --chat-message-font-size: clamp(16px, 3.333vw, 18px);
+  --chat-message-line-height: 1.5;
+
   display: flex;
   flex-direction: column;
   height: var(--app-viewport-height, 100dvh);
diff --git a/src/app/chat/components/text-bubble.module.css b/src/app/chat/components/text-bubble.module.css
index d257b084..bfe00367 100644
--- a/src/app/chat/components/text-bubble.module.css
+++ b/src/app/chat/components/text-bubble.module.css
@@ -6,8 +6,8 @@
   align-self: stretch;
   padding: var(--spacing-3, 12px) var(--spacing-4, 16px);
   border-radius: var(--radius-xxl, 24px);
-  font-size: var(--responsive-body, var(--font-size-body-lg, 16px));
-  line-height: 1.45;
+  font-size: var(--chat-message-font-size, var(--responsive-body, 16px));
+  line-height: var(--chat-message-line-height, 1.5);
   white-space: pre-wrap;
   word-break: break-word;
   box-shadow: var(--shadow-input-box, 0 1px 2px rgba(0, 0, 0, 0.1));