diff --git a/docs/source/conf.py b/docs/source/conf.py
index 9111af1..db6f1bd 100644
--- a/docs/source/conf.py
+++ b/docs/source/conf.py
@@ -1,9 +1,9 @@
 from matplotlib import cycler
 
 project = 'legendkit'
-copyright = '2023, Mr-Milk'
+copyright = '2024, Mr-Milk'
 author = 'Mr-Milk'
-release = '0.3.2'
+release = '0.3.3'
 
 extensions = [
     'numpydoc',
diff --git a/legendkit/_colorart.py b/legendkit/_colorart.py
index c28fc96..744cb62 100644
--- a/legendkit/_colorart.py
+++ b/legendkit/_colorart.py
@@ -386,7 +386,7 @@ def _make_cbar_box(self):
 
         if self.title is not None:
             if self.title_fontproperties is None:
-                textprops = dict(fontweight=600, fontsize=self.title_fontsize)
+                textprops = dict(fontweight='bold', fontsize=self.title_fontsize)
             else:
                 textprops = dict(fontproperties=self.title_fontproperties)
             title_canvas = TextArea(self.title, textprops=textprops)
diff --git a/legendkit/_colorbar.py b/legendkit/_colorbar.py
index 7d6534b..ce11ce2 100644
--- a/legendkit/_colorbar.py
+++ b/legendkit/_colorbar.py
@@ -141,7 +141,7 @@ def __init__(
 
         if title is not None:
             if title_fontproperties is None:
-                title_fontproperties = {'weight': 600, 'size': 'medium'}
+                title_fontproperties = {'weight': 'bold', 'size': 'medium'}
             self.ax.set_title(title, loc=alignment,
                               fontdict=title_fontproperties)
         self.ax.set_facecolor('none')
diff --git a/legendkit/_legend.py b/legendkit/_legend.py
index 336c603..22cf996 100644
--- a/legendkit/_legend.py
+++ b/legendkit/_legend.py
@@ -279,7 +279,7 @@ def val_or_rc(val, rc_name):
             bbox_to_anchor=bbox_to_anchor,
             bbox_transform=bbox_transform,
             # Make the title bold if user supply no style
-            title_fontproperties={'weight': 600},
+            title_fontproperties={'weight': 'bold'},
             handler_map=handler_map,
             fontsize=self._fontsize,
             handleheight=self.handleheight,
diff --git a/legendkit/layout.py b/legendkit/layout.py
index e71b9f2..13f68bc 100644
--- a/legendkit/layout.py
+++ b/legendkit/layout.py
@@ -123,7 +123,7 @@ def stack(legends,
                            )
     if title is not None:
         if title_fontproperties is None:
-            title_fontproperties = {'weight': 600}
+            title_fontproperties = {'weight': 'bold'}
         title_box = TextArea(title, textprops=title_fontproperties)
 
         content = [title_box, children_pack]
diff --git a/pyproject.toml b/pyproject.toml
index b7321d9..c43c002 100644
--- a/pyproject.toml
+++ b/pyproject.toml
@@ -1,6 +1,6 @@
 [tool.poetry]
 name = "legendkit"
-version = "0.3.2"
+version = "0.3.3"
 description = "Legend creation and manipulation with ease for matplotlib"
 authors = ["Mr-Milk <yb97643@um.edu.mo>"]
 license = "MIT"
diff --git a/readthedocs.yaml b/readthedocs.yaml
index 7e83e71..3c1c372 100644
--- a/readthedocs.yaml
+++ b/readthedocs.yaml
@@ -9,5 +9,4 @@ python:
   install:
     - requirements: docs/requirements.txt
     - method: pip
-      path: .
-  system_packages: true
\ No newline at end of file
+      path: .
\ No newline at end of file