diff --git a/plugin/data_types.py b/plugin/data_types.py
index 52ab020..0d144da 100644
--- a/plugin/data_types.py
+++ b/plugin/data_types.py
@@ -12,6 +12,7 @@
 
 POINT = int
 TUPLE_REGION = Tuple[POINT, POINT]
+INDENT_LEVEL = int
 
 if sys.version_info >= (3, 11):
     from enum import StrEnum
@@ -41,7 +42,7 @@ def indent_length(self) -> int:
 
     @cached_property
     def indent_pattern(self) -> str:
-        return rf"^({self.indent_chars})+"
+        return rf"^(?:{self.indent_chars})+"
 
     @cached_property
     def indent_pattern_compiled(self) -> Pattern[str]:
diff --git a/plugin/helpers.py b/plugin/helpers.py
index f84e72e..14ffd3d 100644
--- a/plugin/helpers.py
+++ b/plugin/helpers.py
@@ -13,7 +13,7 @@ def is_renderable_view(view: sublime.View) -> bool:
     # activation by plugin's logics
     return bool(
         view.is_valid()
-        and view.element() is None
+        and not view.element()
         and not is_transient_view(view)
         and (syntax := view.syntax())
         and sublime.score_selector(syntax.scope, get_enabled_selector()) > 0
diff --git a/plugin/settings.py b/plugin/settings.py
index 8146c93..f401601 100644
--- a/plugin/settings.py
+++ b/plugin/settings.py
@@ -31,8 +31,6 @@ def get_plugin_setting(key: str) -> Any: ...
 def get_plugin_setting(key: str, default: None) -> Any: ...
 @overload
 def get_plugin_setting(key: str, default: _T) -> _T: ...
-
-
 def get_plugin_setting(key: str, default: Any = None) -> Any:
     return get_plugin_settings().get(key, default)
 
diff --git a/plugin/view_manager.py b/plugin/view_manager.py
index f3e1475..f81a467 100644
--- a/plugin/view_manager.py
+++ b/plugin/view_manager.py
@@ -6,7 +6,7 @@
 
 import sublime
 
-from .data_types import IndentInfo, LevelStyle
+from .data_types import INDENT_LEVEL, IndentInfo, LevelStyle
 from .helpers import get_regions_key
 from .indent_renderer import AbstractIndentRenderer, find_indent_renderer
 from .settings import get_level_colors, get_level_style
@@ -17,9 +17,9 @@ def calcualte_level_regions(
     *,
     indent_info: IndentInfo | None = None,
     regions: Sequence[sublime.Region] | None = None,
-) -> defaultdict[int, list[sublime.Region]]:
+) -> defaultdict[INDENT_LEVEL, list[sublime.Region]]:
     """
-    Calculates the begin point of indents for each level.
+    Calculates regions of indents for each level.
 
     :param      view:         The view.
     :param      indent_info:  The indent information.
@@ -36,7 +36,7 @@ def calcualte_level_regions(
         regions = (sublime.Region(0, view.size()),)
 
     whole_content = view.substr(sublime.Region(0, view.size()))
-    level_regions: defaultdict[int, list[sublime.Region]] = defaultdict(list)
+    level_regions: defaultdict[INDENT_LEVEL, list[sublime.Region]] = defaultdict(list)
     for region in regions:
         for m in indent_info.indent_pattern_compiled.finditer(whole_content, region.begin(), region.end()):
             for level, level_pt in enumerate(range(m.start(), m.end(), indent_info.indent_length)):