优化块编辑器大纲导航栏

frontend/src/core/features/block_editor/BlockEditorEntry.vue

@@ -395,14 +395,6 @@ onBeforeUnmount(() => {
   z-index: 10;
 }
 
-.blockeditor-container .n-affix--affixed ~ .blockeditor-outline-rail-wrapper {
-  position: fixed;
-  top: calc(64px + 100px);
-  bottom: 12px;
-  left: calc(var(--be-container-left) + var(--be-container-width) - 30px);
-  right: auto;
-}
-
 /* ── ProseMirror ── */
 .blockeditor-mount .ProseMirror { outline: none; min-height: 120px; padding-left: 48px; padding-right: 36px; }
 .blockeditor-mount .ProseMirror > * + * { margin-top: 0.5em; }

frontend/src/core/features/block_editor/menus/BlockOutlineRail.vue

@@ -113,9 +113,9 @@ function syncActive() {
       return
     }
 
-    // 找到视口内最近的 heading（触发线位于导航栏下方 15% 可用高度处）
+    // 找到视口内最近的 heading（触发线对齐 scrollToBlock 的落点，位于导航栏下方 8px 处）
     const contentTop = getContentTop()
-    const triggerY = contentTop + (window.innerHeight - contentTop) * 0.15
+    const triggerY = contentTop + 8
 
     let closest: BlockInfo | null = null
     let minDist = Infinity
@@ -222,16 +222,46 @@ function updateRailPosition() {
   if (!container) return
 
   const editorRect = container.getBoundingClientRect()
+  const rail = railRef.value
 
   // 如果编辑器不在视口内，隐藏 rail
   if (editorRect.bottom < 0 || editorRect.top > window.innerHeight) {
-    railRef.value.style.opacity = '0'
-    railRef.value.style.pointerEvents = 'none'
+    rail.style.opacity = '0'
+    rail.style.pointerEvents = 'none'
     return
   }
 
-  railRef.value.style.opacity = '1'
-  railRef.value.style.pointerEvents = 'auto'
+  rail.style.opacity = '1'
+  rail.style.pointerEvents = 'auto'
+
+  // ── JS-driven position:fixed ──
+  // position:sticky 在 position:absolute 父容器中不可靠（工具栏隐藏时容器高度变化会触发该边界情况）
+  // 故改用 JS 在滚动时精确设置 fixed 位置
+  const stickyTop = getContentTop()
+
+  if (editorRect.top < stickyTop) {
+    // 编辑器已上滚 → 固定 rail 在视口中
+    const wrapper = container.querySelector('.blockeditor-outline-rail-wrapper') as HTMLElement | null
+    if (!wrapper) return
+    const wrapperRect = wrapper.getBoundingClientRect()
+
+    rail.style.position = 'fixed'
+    rail.style.top = `${stickyTop + 8}px`
+    rail.style.left = `${wrapperRect.left}px`
+    rail.style.width = `${wrapperRect.width}px`
+    rail.style.bottom = ''
+    rail.style.right = ''
+    rail.style.zIndex = '10'
+  } else {
+    // 编辑器在视口中 → 由父级 absolute 定位控制
+    rail.style.position = ''
+    rail.style.top = ''
+    rail.style.left = ''
+    rail.style.width = ''
+    rail.style.bottom = ''
+    rail.style.right = ''
+    rail.style.zIndex = ''
+  }
 }
 
 function onRailEnter() {
@@ -426,8 +456,6 @@ onBeforeUnmount(() => {
 <style scoped>
 /* 导航条容器 */
 .block-outline-rail {
-  position: sticky;
-  top: 64px;           /* 页面导航栏底部 */
   width: 16px;
   margin-left: auto;    /* 推至编辑器右侧 */
   pointer-events: auto;