diff --git a/TeXmacs/progs/texmacs/texmacs/tm-files.scm b/TeXmacs/progs/texmacs/texmacs/tm-files.scm
index 44331c9b35..29c7b474cf 100644
--- a/TeXmacs/progs/texmacs/texmacs/tm-files.scm
+++ b/TeXmacs/progs/texmacs/texmacs/tm-files.scm
@@ -105,6 +105,15 @@
   (with t (tree->stree (get-style-tree))
     (and (pair? t) (== (car t) 'tuple) (null? (cdr t)))))
 
+(tm-define (sync-buffer-dark-style-with-gui-theme . opt-buf)
+  (with buf (if (null? opt-buf) (current-buffer) (car opt-buf))
+    (with-buffer buf
+      (if (== (get-preference "gui theme") "liii-night")
+          (when (not (has-style-package? "dark"))
+            (add-style-package "dark"))
+          (when (has-style-package? "dark")
+            (remove-style-package "dark"))))))
+
 (tm-define (buffer-set-default-style)
   (init-style "generic")
   (with lan (get-preference "language")
@@ -120,9 +129,7 @@
     (init-env "prog-scripts" (get-preference "scripting language")))
   (add-style-package "number-europe")
   (add-style-package "preview-ref")
-  (when (== (get-preference "gui theme") "liii-night")
-    (when (not (has-style-package? "dark"))
-      (add-style-package "dark")))
+  (sync-buffer-dark-style-with-gui-theme (current-buffer))
   (buffer-pretend-saved (current-buffer)))
 
 (tm-define (propose-name-buffer)
@@ -583,11 +590,15 @@
   (let* ((path (url->system name))
          (vname `(verbatim ,(utf8->cork path))))
     (cond ((buffer-exists? name)
-           (load-buffer-open name opts))
+           (begin
+             (load-buffer-open name opts)
+             (sync-buffer-dark-style-with-gui-theme name)))
           ((url-exists? name)
            (if (buffer-load name)
                (set-message `(concat "Could not load " ,vname) "Load file")
-               (load-buffer-open name opts)))
+               (begin
+                 (load-buffer-open name opts)
+                 (sync-buffer-dark-style-with-gui-theme name))))
           (else
             (with msg "The file or buffer does not exist:"
               (begin
diff --git a/devel/204_30.md b/devel/204_30.md
new file mode 100644
index 0000000000..847cee79bd
--- /dev/null
+++ b/devel/204_30.md
@@ -0,0 +1,38 @@
+[204_30] 文档主题跟随软件主题，保存时不保留dark
+
+## 如何测试
+
+测试项一：界面主题从浅色切换为深色
+1. 在浅色主题下打开任意 tmu 文件A，文档为浅色背景
+2. 切换主题为深色，自动重启
+3. 深色主题打开后，文件A没有自动变成深色背景，必须要重新打开 tmu 文件A，文档才应该变为深色背景
+
+测试项二：界面主题从深色切换为浅色
+1. 在深色主题下打开任意 tmu 文件B，文档为深色背景
+2. 切换主题为浅色，自动重启
+3. 浅色主题打开后，tmu 文件B应该自动变为浅色背景
+
+测试项三：已经打开的文档重复打开，可以跟随主题颜色变化
+1. 在深色背景下打开任意 tmu 文件C，文档为深色背景
+2. 将文档切换为浅色背景，切换入口位于焦点工具栏的 “主题” 按钮
+3. 通过 “最近打开” 功能，再次点击当前文档，即重复打开当前文档，文档应该从浅色变为深色
+
+测试项四：保存到磁盘的文档不应携带 dark 的 style
+1. 进入软件的深色主题
+2. 在深色主题下，打开任意 tmu 文档，文档背景色应为深色
+3. 触发一次保存
+4. 使用 vscode 或其他纯文本编辑器，打开刚刚保存的 tmu 文档，查看 tmu 头部的 style 块，不应该携带 dark 字样
+
+## 2026/03/31 文档主题跟随软件主题，保存时不保留dark
+
+### What
+让所有文档的背景色跟随软件主题变化，保持视觉上的一致性。
+在保存文档时过滤掉 style 的影响，所有文档都应以浅色背景被保存。
+
+### Why
+目前文档主题依赖于文档本身的 style，即便在深色主题下，以浅色创建的文档不会跟随主题显示为深色
+
+### How
+TeXmacs/progs/texmacs/texmacs/tm-files.scm :108 添加 sync-buffer-dark-style-with-gui-theme 函数，根据当前主题颜色调整文档的背景色
+TeXmacs/progs/texmacs/texmacs/tm-files.scm :588 load-buffer-load 函数，应用 sync-buffer-dark-style-with-gui-theme 函数
+
diff --git a/src/Texmacs/Data/new_buffer.cpp b/src/Texmacs/Data/new_buffer.cpp
index aeb0b69889..2c9e8051d2 100644
--- a/src/Texmacs/Data/new_buffer.cpp
+++ b/src/Texmacs/Data/new_buffer.cpp
@@ -567,6 +567,24 @@ bool
 buffer_export (url name, url dest, string fm) {
   tm_view vw= concrete_view (get_recent_view (name));
   ASSERT (vw != NULL, "view expected");
+  new_data export_data;
+
+  vw->ed->get_data (vw->buf->data);
+  export_data->project= copy (vw->buf->data->project);
+  export_data->style  = copy (vw->buf->data->style);
+  export_data->init   = copy (vw->buf->data->init);
+  export_data->fin    = copy (vw->buf->data->fin);
+  export_data->ref    = copy (vw->buf->data->ref);
+  export_data->aux    = copy (vw->buf->data->aux);
+  export_data->att    = copy (vw->buf->data->att);
+
+  if (export_data->style == "dark") export_data->style= tree (TUPLE);
+  else if (is_func (export_data->style, TUPLE)) {
+    tree style (TUPLE);
+    for (int i= 0; i < N (export_data->style); ++i)
+      if (export_data->style[i] != "dark") style << export_data->style[i];
+    export_data->style= style;
+  }
 
   if (fm == "postscript" || fm == "pdf") {
     int old_stamp= last_modified (dest);
@@ -581,8 +599,7 @@ buffer_export (url name, url dest, string fm) {
   // if (fm == "latex")
   // body= vw->ed->exec_latex (body);
 
-  vw->ed->get_data (vw->buf->data);
-  tree doc= attach_data (body, vw->buf->data, !vw->ed->get_save_aux ());
+  tree doc= attach_data (body, export_data, !vw->ed->get_save_aux ());
 
   if (fm == "latex")
     doc= change_doc_attr (doc, "view", as_string (abstract_view (vw)));
@@ -680,4 +697,4 @@ move_buffer_via_index (int from, int to) {
       swap (bufs[i], bufs[i - 1]);
     }
   }
-}
\ No newline at end of file
+}