正文组成的前端在验收时隔离预览，避免模板脚本碰到宿主页面。

超限只展示源码，测试钉住沙箱和文档拼装。

Co-authored-by: Cursor <cursoragent@cursor.com>

web/styles.css

@@ -3894,6 +3894,38 @@ body.design-workspace .af-mosaic {
 .af-section:last-child {
   margin-bottom: 0;
 }
+.present-preview-note,
+.present-preview-status {
+  margin: 0 0 8px;
+  font-size: 12px;
+  line-height: 1.45;
+  color: var(--muted);
+}
+.present-frame-host {
+  width: 100%;
+  min-width: 0;
+  border: 1px solid var(--border);
+  border-radius: 10px;
+  overflow: hidden;
+  background: var(--surface);
+}
+.present-preview-frame {
+  display: block;
+  width: 100%;
+  height: 220px;
+  border: 0;
+  background: transparent;
+}
+.present-preview-fallback {
+  margin-top: 8px;
+  padding: 8px 10px;
+  border-radius: 8px;
+  background: var(--bg);
+  white-space: pre-wrap;
+  word-break: break-word;
+  font-size: 13px;
+  line-height: 1.55;
+}
 .af-section-title {
   margin: 0 0 8px;
   font-family: var(--font-ui);