diff --git a/cpp/apps/primitives_gallery/main.cpp b/cpp/apps/primitives_gallery/main.cpp
index d2c513b0..c831e7d9 100644
--- a/cpp/apps/primitives_gallery/main.cpp
+++ b/cpp/apps/primitives_gallery/main.cpp
@@ -20,6 +20,7 @@
 #include "demo.h"
 #include "capture.h"
 
+#include <cmath>
 #include <cstdio>
 #include <cstring>
 #include <string>
@@ -154,6 +155,20 @@ static void render() {
         ImGui::BeginChild("##gallery_content", ImVec2(0, 0),
                           ImGuiChildFlags_Borders,
                           ImGuiWindowFlags_HorizontalScrollbar);
+        // Cuando cambia el tamaño de fuente (Settings > Size), el contenido
+        // del child crece/encoge pero la posicion de scroll en pixeles
+        // no — efecto: lo visible "se baja". Escalamos scroll_y por el
+        // ratio de fuentes para mantener la misma linea logica arriba.
+        {
+            static float s_prev_font_size = 0.0f;
+            float cur_font_size = ImGui::GetStyle().FontSizeBase;
+            if (s_prev_font_size > 0.0f &&
+                std::fabs(s_prev_font_size - cur_font_size) > 0.01f) {
+                ImGui::SetScrollY(ImGui::GetScrollY() *
+                                  (cur_font_size / s_prev_font_size));
+            }
+            s_prev_font_size = cur_font_size;
+        }
         const DemoEntry* d = find_demo(g_selected_id);
         if (d && d->fn) d->fn();
         ImGui::EndChild();