diff --git a/public/static/common/css/theme/_fresh.scss b/public/static/common/css/theme/_fresh.scss
index 6099360..5f38dcc 100644
--- a/public/static/common/css/theme/_fresh.scss
+++ b/public/static/common/css/theme/_fresh.scss
@@ -634,6 +634,17 @@ $shadow-pop: 0 6px 16px rgba(31, 35, 41, .08);
     color: $main;
 }
 
+// G3b 经典 brief tab 下划线（用户线上反馈补盖）：layui.css
+// `.layui-tab-brief>.layui-tab-more li.layui-this:after,
+//  .layui-tab-brief>.layui-tab-title .layui-this:after{border-bottom:2px solid #16b777}`
+// G3 初版只盖了 brief 字色、漏了此条——system.config 页实测字蓝线绿。精确镜像
+// brief 限定选择器（包裹后 (0,3,1)/(0,4,1) 必胜），不带 brief 的"白线融合"变体
+// （.layui-tab-title .layui-this:after 底线 #fff）不受牵连。
+.layui-tab-brief > .layui-tab-more li.layui-this:after,
+.layui-tab-brief > .layui-tab-title .layui-this:after {
+    border-bottom-color: $main;
+}
+
 // G4 分页（#16baaa）
 .layui-laypage .layui-laypage-curr .layui-laypage-em {
     background-color: $main;
diff --git a/public/static/common/css/theme/index.css b/public/static/common/css/theme/index.css
index f050df6..902a1f8 100644
--- a/public/static/common/css/theme/index.css
+++ b/public/static/common/css/theme/index.css
@@ -2580,6 +2580,10 @@
 .elem-style-fresh .layui-tab-brief > .layui-tab-title .layui-this {
   color: #1E9FFF;
 }
+.elem-style-fresh .layui-tab-brief > .layui-tab-more li.layui-this:after,
+.elem-style-fresh .layui-tab-brief > .layui-tab-title .layui-this:after {
+  border-bottom-color: #1E9FFF;
+}
 .elem-style-fresh .layui-laypage .layui-laypage-curr .layui-laypage-em {
   background-color: #1E9FFF;
 }