diff --git a/.gitignore b/.gitignore
index eba74f4..4ea05a1 100644
--- a/.gitignore
+++ b/.gitignore
@@ -1 +1,2 @@
-venv/
\ No newline at end of file
+venv/
+__pycache__/
\ No newline at end of file
diff --git a/app.py b/app.py
index e07fd05..96172d0 100644
--- a/app.py
+++ b/app.py
@@ -47,7 +47,8 @@
 st.set_page_config(
     page_title="IVUS合併症アノテーションツール",
     page_icon="🫀",
-    layout="wide"
+    layout="wide",
+    initial_sidebar_state="expanded"  # Hide sidebar to prevent scrolling
 )
 
 
@@ -275,6 +276,10 @@
             st.session_state.annotator
         )
 
+    # Initialize zoom level (persistent across cases)
+    if 'zoom_percent' not in st.session_state:
+        st.session_state.zoom_percent = 80  # Default zoom level
+
 
 def get_current_case_id() -> Optional[Union[int, float]]:
     """現在の症例IDを取得。"""
@@ -284,69 +289,67 @@
     return None
 
 
-def render_header():
-    """進捗情報を含むヘッダーを表示。"""
-    st.title("IVUS合併症アノテーションツール")
-
-    total_cases = len(st.session_state.case_ids)
-    annotated_count = len(st.session_state.annotated_cases)
-
-    col1, col2, col3, col4 = st.columns(4)
-    with col1:
-        st.metric("アノテーター", st.session_state.annotator)
-    with col2:
-        st.metric("全症例数", total_cases)
-    with col3:
-        st.metric("完了数", annotated_count)
-    with col4:
-        progress = annotated_count / total_cases if total_cases > 0 else 0
-        st.metric("進捗", f"{progress:.1%}")
-
-
-def render_case_selector(container):
-    """症例ナビゲーションを表示（右側に配置）。
-
-    Args:
-        container: Streamlit container to render in
+def render_sidebar_ui():
     """
-    container.header("症例ナビゲーション")
-
-    current_case_id = get_current_case_id()
-
-    # Case selector dropdown
-    case_display = [
-        f"症例 {cid}" + (" ✓" if cid in st.session_state.annotated_cases else "")
-        for cid in st.session_state.case_ids
-    ]
-
-    selected_idx = container.selectbox(
-        "症例を選択",
-        range(len(st.session_state.case_ids)),
-        index=st.session_state.current_case_idx,
-        format_func=lambda i: case_display[i]
-    )
-
-    if selected_idx != st.session_state.current_case_idx:
-        st.session_state.current_case_idx = selected_idx
-        st.rerun()
-
-    # Previous/Next buttons
-    col1, col2 = container.columns(2)
-    with col1:
-        if st.button("← 前へ", disabled=st.session_state.current_case_idx == 0):
-            st.session_state.current_case_idx -= 1
-            st.rerun()
-    with col2:
-        if st.button(
-            "次へ →",
-            disabled=st.session_state.current_case_idx >= len(st.session_state.case_ids) - 1
-        ):
-            st.session_state.current_case_idx += 1
+    サイドバーに進捗、ナビゲーション、設定を集約。
+    メイン画面の縦スペースを確保するために使用。
+    """
+    with st.sidebar:
+        st.header(f"担当: {st.session_state.annotator}")
+        
+        # --- 進捗状況 ---
+        total_cases = len(st.session_state.case_ids)
+        annotated_count = len(st.session_state.annotated_cases)
+        progress = annotated_count / total_cases if total_cases > 0 else 0
+        st.progress(progress)
+        st.caption(f"進捗: {progress:.1%} ({annotated_count}/{total_cases})")
+        
+        st.markdown("---")
+        
+        # --- 症例ナビゲーション ---
+        st.subheader("症例選択")
+        current_case_id = get_current_case_id()
+        case_display = [
+            f"症例 {cid}" + (" ✓" if cid in st.session_state.annotated_cases else "")
+            for cid in st.session_state.case_ids
+        ]
+        
+        selected_idx = st.selectbox(
+            "症例リスト",
+            range(len(st.session_state.case_ids)),
+            index=st.session_state.current_case_idx,
+            format_func=lambda i: case_display[i],
+            label_visibility="collapsed"
+        )
+        
+        if selected_idx != st.session_state.current_case_idx:
+            st.session_state.current_case_idx = selected_idx
             st.rerun()
 
-    # Display current case info
-    if current_case_id:
-        container.info(f"**現在の症例:** {current_case_id}")
+        col1, col2 = st.columns(2)
+        with col1:
+            if st.button("← 前へ", disabled=st.session_state.current_case_idx == 0, use_container_width=True):
+                st.session_state.current_case_idx -= 1
+                st.rerun()
+        with col2:
+            if st.button("次へ →", disabled=st.session_state.current_case_idx >= len(st.session_state.case_ids) - 1, use_container_width=True):
+                st.session_state.current_case_idx += 1
+                st.rerun()
+        
+        st.markdown("---")
+
+        # --- 画像拡大率 ---
+        st.subheader("表示設定")
+        zoom_percent = st.select_slider(
+            "画像拡大率",
+            options=[30, 40, 50, 60, 70, 80, 90, 100, 110, 120, 130, 140, 150],
+            value=st.session_state.zoom_percent,
+            format_func=lambda x: f"{x}%",
+            key="global_zoom"
+        )
+        if zoom_percent != st.session_state.zoom_percent:
+            st.session_state.zoom_percent = zoom_percent
+            st.rerun()
 
 
 def render_image_viewer(case_id: Union[int, float], container):
@@ -368,16 +371,6 @@
     if frame_key not in st.session_state:
         st.session_state[frame_key] = 0
 
-    # Image zoom slider (拡大率の調整)
-    zoom_percent = container.slider(
-        "画像拡大率 (%)",
-        min_value=30,
-        max_value=150,
-        value=80,  # デフォルト値を少し縮小
-        step=10,
-        key=f"zoom_{case_id}"
-    )
-
     # Image slider
     frame_idx = container.slider(
         "フレーム番号",
@@ -392,12 +385,12 @@
     if frame_idx != st.session_state[frame_key]:
         st.session_state[frame_key] = frame_idx
 
-    # Display image with custom width
+    # Display image with custom width based on global zoom level
     try:
         img = Image.open(images[frame_idx])
 
-        # Calculate display width based on zoom percentage
-        display_width = int(DEFAULT_IMAGE_WIDTH * zoom_percent / 100)
+        # Calculate display width based on zoom percentage from session state
+        display_width = int(DEFAULT_IMAGE_WIDTH * st.session_state.zoom_percent / 100)
 
         container.image(
             img,
@@ -426,55 +419,46 @@
 
 
 def render_annotation_form(container, case_id: Union[int, float]) -> dict:
-    """
-    アノテーション入力フォームを表示。
-
-    Args:
-        container: Streamlit container to render in
-        case_id: 現在の症例ID
-
-    Returns:
-        アノテーションデータの辞書
-    """
-    container.markdown("---")
-    container.header("アノテーション")
-
-    # Display annotator name (read-only)
-    container.text(f"アノテーター: {st.session_state.annotator}")
-    container.markdown("---")
-
-    # Q1: Prediction
+    """アノテーション入力フォームを表示 - コンパクト版"""
+    
+    # Q1: Prediction (横並び)
+    container.markdown("**Q1: 合併症予測**")
     prediction = container.radio(
-        "Q1: 合併症予測 (No reflow/Slow flow)",
+        "Q1: 合併症予測",
         PREDICTION_OPTIONS,
-        key=f"prediction_{case_id}"
+        key=f"prediction_{case_id}",
+        horizontal=True,  # 変更: 横並びにして省スペース化
+        label_visibility="collapsed"
     )
 
-    # Q2: Confidence (5段階、横並び)
-    container.markdown("**Q2: 確信度 (%)**")
+    # Q2: Confidence (横並び)
+    container.markdown("**Q2: 確信度**")
     confidence = container.radio(
-        "確信度を選択",
+        "確信度",
         CONFIDENCE_OPTIONS,
-        index=2,  # デフォルトは50%
+        index=2,  # 50%
         format_func=lambda x: f"{x}%",
         key=f"confidence_{case_id}",
         label_visibility="collapsed",
-        horizontal=True  # 横並びに表示
+        horizontal=True  # 変更: 横並び
     )
 
     # Q3: Reasons
-    container.markdown("**Q3: 判断根拠** (複数選択可)")
+    container.markdown("**Q3: 判断根拠**")
     reasons = []
+    # チェックボックスは項目の長さによるため縦並びのまま
     for reason in REASONS_OPTIONS:
         if container.checkbox(reason, key=f"reason_{case_id}_{reason}"):
             reasons.append(reason)
 
-    # Q4: Free text comment
+    # Q4: Comment (高さを最小限に)
+    container.markdown("**Q4: 自由記述**")
     comment = container.text_area(
-        "Q4: 自由記述欄",
+        "Q4: 自由記述",
         value="",
         key=f"comment_{case_id}",
-        height=100
+        height=68,  # 変更: 高さを約2行分に縮小
+        label_visibility="collapsed"
     )
 
     return {
@@ -573,7 +557,7 @@
         st.info("アプリケーションを再起動して、データディレクトリパスを確認してください。")
         return
 
-    render_header()
+    render_sidebar_ui()
 
     current_case_id = get_current_case_id()
 
@@ -599,9 +583,6 @@
 
     # Right side: Navigation and Annotation
     with right_col:
-        # Navigation section
-        render_case_selector(right_col)
-
         # Annotation form section
         annotation_data = render_annotation_form(right_col, current_case_id)