diff --git a/frontend/src/components/shared/ButtonSelector.tsx b/frontend/src/components/shared/ButtonSelector.tsx
index bc95134d6..a45936f6a 100644
--- a/frontend/src/components/shared/ButtonSelector.tsx
+++ b/frontend/src/components/shared/ButtonSelector.tsx
@@ -1,4 +1,5 @@
 import { Button, Group, Stack, Text } from "@mantine/core";
+import FitText from "./FitText";
 
 export interface ButtonOption<T> {
   value: T;
@@ -13,6 +14,8 @@ interface ButtonSelectorProps<T> {
   label?: string;
   disabled?: boolean;
   fullWidth?: boolean;
+  buttonClassName?: string;
+  textClassName?: string;
 }
 
 const ButtonSelector = <T extends string>({
@@ -22,6 +25,8 @@ const ButtonSelector = <T extends string>({
   label = undefined,
   disabled = false,
   fullWidth = true,
+  buttonClassName,
+  textClassName,
 }: ButtonSelectorProps<T>) => {
   return (
     <Stack gap='var(--mantine-spacing-sm)'>
@@ -41,6 +46,7 @@ const ButtonSelector = <T extends string>({
             color={value === option.value ? 'var(--color-primary-500)' : 'var(--text-muted)'}
             onClick={() => onChange(option.value)}
             disabled={disabled || option.disabled}
+            className={buttonClassName}
             style={{
               flex: fullWidth ? 1 : undefined,
               height: 'auto',
@@ -48,7 +54,13 @@ const ButtonSelector = <T extends string>({
               fontSize: 'var(--mantine-font-size-sm)'
             }}
           >
-            {option.label}
+            <FitText
+              text={option.label}
+              lines={1}
+              minimumFontScale={0.5}
+              fontSize={10}
+              className={textClassName}
+            />
           </Button>
         ))}
       </Group>
diff --git a/frontend/src/components/tools/addStamp/StampPreview.module.css b/frontend/src/components/tools/addStamp/StampPreview.module.css
index f7e5c5c3c..779d7bf1d 100644
--- a/frontend/src/components/tools/addStamp/StampPreview.module.css
+++ b/frontend/src/components/tools/addStamp/StampPreview.module.css
@@ -127,7 +127,9 @@
 /* Information text container */
 .informationContainer {
   background-color: var(--information-text-bg);
-  padding: 8px;
+  padding: 2px;
+  padding-left: 8px;
+  padding-right: 8px;
   border-radius: 10px;
   margin-top: 8px;
   margin-bottom: 8px;
@@ -138,8 +140,8 @@
 }
 
 .informationText {
-  font-size: 0.875rem;
-  font-weight: 500;
+  font-size: 0.75rem;
+  font-weight: 400;
   color: var(--information-text-color);
 }
 
diff --git a/frontend/src/components/tools/addStamp/StampPreview.tsx b/frontend/src/components/tools/addStamp/StampPreview.tsx
index 7d94ac20f..62eed20b4 100644
--- a/frontend/src/components/tools/addStamp/StampPreview.tsx
+++ b/frontend/src/components/tools/addStamp/StampPreview.tsx
@@ -110,6 +110,48 @@ export default function StampPreview({ parameters, onParameterChange, file, show
     )
   ), [containerSize, parameters, imageMeta, pageSize, showQuickGrid, hoverTile, pageThumbnail]);
 
+  // Keep center fixed when scaling via slider (or any fontSize changes)
+  const prevDimsRef = useRef<{ fontSize: number; widthPx: number; heightPx: number; leftPx: number; bottomPx: number } | null>(null);
+  useEffect(() => {
+    const itemStyle = style.item as any;
+    if (!itemStyle || containerSize.width <= 0 || containerSize.height <= 0) return;
+
+    const parse = (v: any) => parseFloat(String(v).replace('px', '')) || 0;
+    const leftPx = parse(itemStyle.left);
+    const bottomPx = parse(itemStyle.bottom);
+    const widthPx = parse(itemStyle.width);
+    const heightPx = parse(itemStyle.height);
+
+    const prev = prevDimsRef.current;
+    const hasOverrides = parameters.overrideX >= 0 && parameters.overrideY >= 0;
+    const canAdjust = hasOverrides && !showQuickGrid;
+    if (
+      prev &&
+      canAdjust &&
+      parameters.fontSize !== prev.fontSize &&
+      prev.widthPx > 0 &&
+      prev.heightPx > 0 &&
+      widthPx > 0 &&
+      heightPx > 0
+    ) {
+      const centerX = prev.leftPx + prev.widthPx / 2;
+      const centerY = prev.bottomPx + prev.heightPx / 2;
+      const newLeftPx = centerX - widthPx / 2;
+      const newBottomPx = centerY - heightPx / 2;
+
+      const widthPts = pageSize?.widthPts ?? 595.28;
+      const heightPts = pageSize?.heightPts ?? 841.89;
+      const scaleX = containerSize.width / widthPts;
+      const scaleY = containerSize.height / heightPts;
+      const newLeftPts = Math.max(0, Math.min(containerSize.width, newLeftPx)) / scaleX;
+      const newBottomPts = Math.max(0, Math.min(containerSize.height, newBottomPx)) / scaleY;
+      onParameterChange('overrideX', newLeftPts as any);
+      onParameterChange('overrideY', newBottomPts as any);
+    }
+
+    prevDimsRef.current = { fontSize: parameters.fontSize, widthPx, heightPx, leftPx, bottomPx };
+  }, [parameters.fontSize, style.item, containerSize, pageSize, showQuickGrid, parameters.overrideX, parameters.overrideY, onParameterChange]);
+
   // Drag/resize/rotate interactions
   const draggingRef = useRef<{ type: 'move' | 'resize' | 'rotate'; startX: number; startY: number; initLeft: number; initBottom: number; initHeight: number; centerX: number; centerY: number } | null>(null);
 
diff --git a/frontend/src/components/tools/addStamp/StampPreviewUtils.ts b/frontend/src/components/tools/addStamp/StampPreviewUtils.ts
index 0cd6b8d76..17a4f1bfe 100644
--- a/frontend/src/components/tools/addStamp/StampPreviewUtils.ts
+++ b/frontend/src/components/tools/addStamp/StampPreviewUtils.ts
@@ -192,7 +192,7 @@ export function computeStampPreviewStyle(
       height: `${heightPx}px`,
       opacity: displayOpacity,
       transform: `rotate(${-parameters.rotation}deg)`,
-      transformOrigin: 'left bottom',
+      transformOrigin: 'center center',
       color: parameters.customColor,
       display: 'flex',
       flexDirection: 'column',
diff --git a/frontend/src/components/tools/addStamp/useAddStampOperation.ts b/frontend/src/components/tools/addStamp/useAddStampOperation.ts
index 1ff6b62c6..fe67e9925 100644
--- a/frontend/src/components/tools/addStamp/useAddStampOperation.ts
+++ b/frontend/src/components/tools/addStamp/useAddStampOperation.ts
@@ -9,9 +9,7 @@ export const buildAddStampFormData = (parameters: AddStampParameters, file: File
   formData.append('pageNumbers', parameters.pageNumbers);
   formData.append('customMargin', 'medium'); 
   formData.append('position', String(parameters.position));
-  const effectiveFontSize = parameters.stampType === 'text'
-    ? parameters.fontSize * 2.2 // upscale to match the preview size
-    : parameters.fontSize;
+  const effectiveFontSize = parameters.fontSize;
   formData.append('fontSize', String(effectiveFontSize));
   formData.append('rotation', String(parameters.rotation));
   formData.append('opacity', String(parameters.opacity / 100));
diff --git a/frontend/src/tools/AddStamp.tsx b/frontend/src/tools/AddStamp.tsx
index 61645abc9..704b447cf 100644
--- a/frontend/src/tools/AddStamp.tsx
+++ b/frontend/src/tools/AddStamp.tsx
@@ -12,6 +12,7 @@ import LocalIcon from "../components/shared/LocalIcon";
 import styles from "../components/tools/addStamp/StampPreview.module.css";
 import { Tooltip } from "../components/shared/Tooltip";
 import FitText from "../components/shared/FitText";
+import ButtonSelector from "../components/shared/ButtonSelector";
 
 const AddStamp = ({ onPreviewFile, onComplete, onError }: BaseToolProps) => {
   const { t } = useTranslation();
@@ -99,24 +100,17 @@ const AddStamp = ({ onPreviewFile, onComplete, onError }: BaseToolProps) => {
         <Stack gap="md" justify="space-between" flex={1}>
           <div>
             <Text size="sm" fw={500} mb="xs">{t('AddStampRequest.stampType', 'Stamp Type')}</Text>
-            <Group className={styles.modeToggleGroup} grow>
-              <Button
-                variant={params.parameters.stampType === 'text' ? 'filled' : 'outline'}
-                className={styles.modeToggleButton}
-                onClick={() => params.updateParameter('stampType', 'text')}
-                disabled={endpointLoading}
-              >
-                {t('watermark.type.1', 'Text')}
-              </Button>
-              <Button
-                variant={params.parameters.stampType === 'image' ? 'filled' : 'outline'}
-                className={styles.modeToggleButton}
-                onClick={() => params.updateParameter('stampType', 'image')}
-                disabled={endpointLoading}
-              >
-                {t('watermark.type.2', 'Image')}
-              </Button>
-            </Group>
+            <ButtonSelector
+              value={params.parameters.stampType}
+              onChange={(v: 'text' | 'image') => params.updateParameter('stampType', v)}
+              options={[
+                { value: 'text', label: t('watermark.type.1', 'Text') },
+                { value: 'image', label: t('watermark.type.2', 'Image') },
+              ]}
+              disabled={endpointLoading}
+              buttonClassName={styles.modeToggleButton}
+              textClassName={styles.modeToggleButtonText}
+            />
           </div>
 
           {params.parameters.stampType === 'text' && (
@@ -208,45 +202,31 @@ const AddStamp = ({ onPreviewFile, onComplete, onError }: BaseToolProps) => {
         <Stack gap="md" justify="space-between">
           {/* Mode toggle: Quick grid vs Custom drag - only show for image stamps */}
           {params.parameters.stampType === 'image' && (
-            <Group className={styles.modeToggleGroup} grow>
-              <Button
-                variant={quickPositionModeSelected ? 'filled' : 'outline'}
-                className={styles.modeToggleButton}
-                onClick={() => {
-                  setQuickPositionModeSelected(true);
-                  setCustomPositionModeSelected(false);
-                }}
-              >
-                <FitText
-                  text={t('quickPosition', 'Quick Position')}
-                  lines={1}
-                  minimumFontScale={0.5}
-                  fontSize={10}
-                  className={styles.modeToggleButtonText}
-                />
-              </Button>
-              <Button
-                variant={customPositionModeSelected ? 'filled' : 'outline'}
-                className={styles.modeToggleButton}
-                onClick={() => {
-                  setQuickPositionModeSelected(false);
-                  setCustomPositionModeSelected(true);
-                }}
-              >
-                <FitText
-                  text={t('customPosition', 'Custom Position')}
-                  lines={1}
-                  minimumFontScale={0.5}
-                  fontSize={10}
-                  className={styles.modeToggleButtonText}
-                />
-              </Button>
-            </Group>
+            <ButtonSelector
+              value={quickPositionModeSelected ? 'quick' : 'custom'}
+              onChange={(v: 'quick' | 'custom') => {
+                const isQuick = v === 'quick';
+                setQuickPositionModeSelected(isQuick);
+                setCustomPositionModeSelected(!isQuick);
+              }}
+              options={[
+                { value: 'quick', label: t('quickPosition', 'Quick Position') },
+                { value: 'custom', label: t('customPosition', 'Custom Position') },
+              ]}
+              disabled={endpointLoading}
+              buttonClassName={styles.modeToggleButton}
+              textClassName={styles.modeToggleButtonText}
+            />
           )}
 
           {params.parameters.stampType === 'image' && customPositionModeSelected && (
             <div className={styles.informationContainer}>
-              <Text className={styles.informationText}>{t('customPosition', 'Drag the stamp to the desired location in the preview window.')}</Text>
+              <Text className={styles.informationText}>{t('AddStampRequest.customPosition', 'Drag the stamp to the desired location in the preview window.')}</Text>
+            </div>
+          )}
+          {params.parameters.stampType === 'image' && !customPositionModeSelected && (
+            <div className={styles.informationContainer}>
+              <Text className={styles.informationText}>{t('AddStampRequest.quickPosition', 'Select a position on the page to place the stamp.')}</Text>
             </div>
           )}