diff --git a/src/aiidalab_qe/common/guide_manager.py b/src/aiidalab_qe/common/guide_manager.py
index 9e4e8a75..2bcc6e72 100644
--- a/src/aiidalab_qe/common/guide_manager.py
+++ b/src/aiidalab_qe/common/guide_manager.py
@@ -3,16 +3,20 @@
 from pathlib import Path
 
 import traitlets as tl
-from bs4 import BeautifulSoup
+from bs4 import BeautifulSoup, PageElement
 
 import aiidalab_qe
 from aiidalab_qe.app.utils import get_entry_items
 
 
 class GuideManager(tl.HasTraits):
+    """A global guide manager that loads and manages guide sections."""
+
     active_guide = tl.Unicode("none", allow_none=True)
 
     def __init__(self, *args, **kwargs):
+        """`GuideManager` constructor."""
+
         super().__init__(*args, **kwargs)
         guides = Path(aiidalab_qe.__file__).parent.joinpath("guides").glob("*")
         self._guides = {guide.stem: guide.absolute() for guide in guides}
@@ -26,21 +30,42 @@ def __init__(self, *args, **kwargs):
         )
 
     @property
-    def has_guide(self):
+    def has_guide(self) -> bool:
         return self.active_guide != "none"
 
-    def get_guides(self):
+    def get_guides(self) -> list[str]:
+        """Return a list of available guides.
+
+        Returns
+        -------
+        `list[str]`
+            A list of the names of available guides.
+        """
         return [*self._guides.keys()]
 
-    def get_guide_section_by_id(self, content_id: str):
-        return self.content.find(attrs={"id": content_id})
+    def get_guide_section_by_id(self, content_id: str) -> PageElement | None:
+        """Return a guide section by its HTML `id` attribute.
+
+        Parameters
+        ----------
+        `content_id` : `str`
+            The HTML `id` attribute of the guide section.
+
+        Returns
+        -------
+        `PageElement` | `None`
+            The guide section or `None` if not found.
+        """
+        return self.content.find(attrs={"id": content_id})  # type: ignore
 
     def _on_active_guide_change(self, _):
+        """Load the contents of the active guide."""
         guide_path = self._guides.get(self.active_guide)
         html = Path(guide_path).read_text() if guide_path else ""
         self.content = BeautifulSoup(html, "html.parser")
 
     def _fetch_plugin_guides(self):
+        """Fetch guides from plugins."""
         entries: dict[str, Path] = get_entry_items("aiidalab_qe.properties", "guides")
         for guides in entries.values():
             for guide in guides.glob("*"):
diff --git a/src/aiidalab_qe/common/infobox.py b/src/aiidalab_qe/common/infobox.py
index 841dc762..bdf72e98 100644
--- a/src/aiidalab_qe/common/infobox.py
+++ b/src/aiidalab_qe/common/infobox.py
@@ -23,7 +23,22 @@ def __init__(self, classes: list[str] | None = None, **kwargs):
 
 
 class InAppGuide(InfoBox):
-    """The `InfoAppGuide` is used to set up toggleable in-app guides."""
+    """The `InAppGuide` is used to set up toggleable in-app guides.
+
+    Attributes
+    ----------
+    `manager` : `GuideManager`
+        A local reference to the global guide manager.
+    `identifier` : `str`, optional
+        If content `children` are not provided directly, the `identifier`
+        is used to fetch the corresponding guide section from the guide
+        currently loaded by the guide manager.
+
+    Raises
+    ------
+    `ValueError`
+        If neither content `children` or a guide section `identifier` are provided.
+    """
 
     def __init__(
         self,
@@ -37,9 +52,11 @@ def __init__(
         Parameters
         ----------
         children : `list`, optional
-            The children of the guide.
-        `identifier` : `str`
-            The identifier used to load the guide file.
+            The content children of this guide section.
+        `identifier` : `str`, optional
+            If content `children` are not provided directly, the `identifier`
+            is used to fetch the corresponding guide section from the guide
+            currently loaded by the guide manager.
         `classes` : `list[str]`, optional
             One or more CSS classes.
         """
@@ -71,13 +88,18 @@ def __init__(
         # This manual toggle call is necessary because the guide
         # may be contained in a component that was not yet rendered
         # when a guide was selected.
-        self._toggle_guide()
+        self._on_active_guide_change(None)
 
     def _on_active_guide_change(self, _):
+        self._update_contents()
         self._toggle_guide()
 
-    def _toggle_guide(self):
+    def _update_contents(self):
+        """Update the contents of the guide section."""
         if hasattr(self, "identifier"):
             html = self.manager.get_guide_section_by_id(self.identifier)
             self.children = [ipw.HTML(str(html))] if html else []
+
+    def _toggle_guide(self):
+        """Toggle the visibility of the guide section."""
         self.layout.display = "flex" if self.manager.has_guide else "none"