diff --git a/booru_viewer/gui/app.py b/booru_viewer/gui/app.py
index 6f504e1..fb93fc5 100644
--- a/booru_viewer/gui/app.py
+++ b/booru_viewer/gui/app.py
@@ -1809,6 +1809,28 @@ def run() -> None:
             # Use Fusion style so QSS has full control over rendering
             app.setStyle("Fusion")
             css_text = custom_css.read_text()
+            # Inject spinbox arrow fix if not already styled
+            if "QSpinBox::up-button" not in css_text:
+                css_text += """
+                QSpinBox::up-button, QSpinBox::down-button {
+                    width: 16px;
+                    border: none;
+                }
+                QSpinBox::up-arrow {
+                    image: none;
+                    border-left: 4px solid transparent;
+                    border-right: 4px solid transparent;
+                    border-bottom: 5px solid palette(text);
+                    width: 0; height: 0;
+                }
+                QSpinBox::down-arrow {
+                    image: none;
+                    border-left: 4px solid transparent;
+                    border-right: 4px solid transparent;
+                    border-top: 5px solid palette(text);
+                    width: 0; height: 0;
+                }
+                """
             app.setStyleSheet(css_text)
             # Extract selection color from QSS and apply to palette
             import re