优化滚动条显示逻辑与样式限制

src/layout/chat_layout.vue

@@ -63,7 +63,7 @@
       <div class="flex-1 flex flex-col min-h-0 px-4 pt-4 pb-4 relative z-10">
         <div class="flex items-end justify-between mb-2">
           <div
-            class="flex items-end gap-1 overflow-x-auto scrollbar-custom flex-1"
+            class="flex items-end gap-1 overflow-x-auto overflow-y-hidden scrollbar-custom flex-1"
           >
             <button
               class="px-4 py-2 text-xs font-medium bg-white/30 text-foreground rounded-t-2xl shadow-sm -mb-[1px]"
@@ -77,10 +77,10 @@
             </button>
           </div>
           <button
-            class="w-6 h-6 rounded-md bg-white/40 border border-white/40 flex items-center justify-center text-xs"
+            class="h-9 px-4 rounded-full bg-gradient-to-r from-blue-500 to-blue-400 border border-white/60 shadow-lg text-white flex items-center justify-center text-[11px] font-semibold hover:shadow-xl hover:scale-105 transition-all"
             @click="newConversation"
           >
-            +
+            新会话
           </button>
         </div>
 
@@ -386,7 +386,7 @@
                               ? '输入关键词搜索图片（实时搜索）...'
                               : '请输入工程参数、需求或问题...'
                           "
-                          class="composer-textarea"
+                          :class="['composer-textarea', { 'show-scrollbar': showTextareaScrollbar }]"
                           @keydown="handleKeydown"
                           :disabled="loading"
                         />
@@ -622,7 +622,7 @@
                           <div v-if="msg.isSearchBox" class="search-card">
                             <div class="search-head">
                               <div class="search-head__left">
-                                <span class="mode-pill">🔍 文档检索模式</span>
+                                <span class="mode-pill">文档检索模式</span>
                                 <div>
                                   <p class="head-title">工程档案 · 精准检索</p>
                                   <p class="head-desc">
@@ -1207,7 +1207,7 @@
                         ? '输入关键词搜索图片（实时搜索）...'
                         : '请输入工程参数、需求或问题...'
                     "
-                    class="composer-textarea"
+                    :class="['composer-textarea', { 'show-scrollbar': showTextareaScrollbar }]"
                     @keydown="handleKeydown"
                     :disabled="loading"
                   />
@@ -1854,6 +1854,11 @@ const isSingleLine = computed(() => {
   return !inputText.value.includes('\n') && inputText.value.length < 50
 })
 
+const showTextareaScrollbar = computed(() => {
+  const lines = inputText.value.split(/\r?\n/)
+  return lines.length > 2
+})
+
 const guidePrompts = [
   {
     id: 'knowledge-base',
@@ -3518,12 +3523,15 @@ function terminateProcess(msg, msgIndex) {
   justify-content: space-between;
   gap: 16px;
   margin-bottom: 16px;
+  flex-wrap: nowrap;
+  white-space: nowrap;
 }
 
 .search-head__left {
   display: flex;
   align-items: center;
   gap: 12px;
+  flex-wrap: nowrap;
 }
 
 .mode-pill {
@@ -3544,12 +3552,14 @@ function terminateProcess(msg, msgIndex) {
   font-size: 16px;
   color: hsl(var(--foreground));
   line-height: 1.2;
+  white-space: nowrap;
 }
 
 .head-desc {
   margin-top: 2px;
   font-size: 12px;
   color: hsl(var(--muted-foreground));
+  white-space: nowrap;
 }
 
 .head-stats {
@@ -4386,6 +4396,29 @@ function terminateProcess(msg, msgIndex) {
   padding: 0;
   line-height: 1.6;
   text-align: left;
+  overflow-y: hidden;
+  scrollbar-width: none;
+  -ms-overflow-style: none;
+}
+
+.composer-textarea :deep(.el-textarea__inner::-webkit-scrollbar) {
+  width: 0;
+  height: 0;
+}
+
+.composer-textarea.show-scrollbar :deep(.el-textarea__inner) {
+  overflow-y: auto;
+  scrollbar-width: thin;
+}
+
+.composer-textarea.show-scrollbar :deep(.el-textarea__inner::-webkit-scrollbar) {
+  width: 6px;
+  height: 6px;
+}
+
+.composer-textarea.show-scrollbar :deep(.el-textarea__inner::-webkit-scrollbar-thumb) {
+  background: hsla(220, 20%, 60%, 0.3);
+  border-radius: 999px;
 }
 
 .composer-textarea :deep(.el-textarea__inner):focus {