Redraw if stylesheets is empty (#6365)

panel/models/layout.ts

@@ -34,16 +34,16 @@ export class PanelMarkupView extends WidgetView {
     for (const sts of this._applied_stylesheets) {
       const style_el = (sts as any).el
       if (style_el instanceof HTMLLinkElement) {
-	this._initialized_stylesheets[style_el.href] = false
-	style_el.addEventListener("load", () => {
-	  this._initialized_stylesheets[style_el.href] = true
-	  if (
-	    Object.values(this._initialized_stylesheets).every(Boolean)
-	  )
-	    this.style_redraw()
-	})
+        this._initialized_stylesheets[style_el.href] = false
+        style_el.addEventListener('load', () => {
+          this._initialized_stylesheets[style_el.href] = true
+          if (Object.values(this._initialized_stylesheets).every(Boolean))
+            this.style_redraw()
+        })
       }
     }
+    if (Object.keys(this._initialized_stylesheets).length === 0)
+      this.style_redraw()
   }
 
   style_redraw(): void {

panel/tests/ui/pane/test_markup.py

@@ -1,9 +1,12 @@
+from html import escape
+
 import pytest
 
 pytest.importorskip("playwright")
 
 from playwright.sync_api import expect
 
+from panel.models import HTML
 from panel.pane import Markdown
 from panel.tests.util import serve_component, wait_until
 
@@ -85,3 +88,13 @@ def test_markdown_pane_visible_toggle(page):
     md.visible = True
 
     wait_until(lambda: page.locator(".markdown").locator("div").is_visible(), page)
+
+def test_html_model_no_stylesheet(page):
+    # regression test for https://github.com/holoviz/holoviews/issues/5963
+    text = "<h1>Header</h1>"
+    html = HTML(text=escape(text), width=200, height=200)
+    serve_component(page, html)
+
+    header_element = page.locator('h1:has-text("Header")')
+    assert header_element.is_visible()
+    assert header_element.text_content() == "Header"