diff --git a/gt_extras/colors.py b/gt_extras/colors.py
index f3e9512..ffab65a 100644
--- a/gt_extras/colors.py
+++ b/gt_extras/colors.py
@@ -84,6 +84,13 @@ def gt_highlight_cols(
     gte.gt_highlight_cols(gt, columns="hp")
     ```
     """
+    # Throw if `font_weight` is not one of the allowed values
+    if isinstance(font_weight, str):
+        if font_weight not in ["normal", "bold", "bolder", "lighter"]:
+            raise ValueError("Font_weight must be one of 'normal', 'bold', 'bolder', or 'lighter', or an integer")
+    elif not isinstance(font_weight, (int, float)):
+        raise TypeError("Font_weight must be an int, float, or str")
+
     if alpha:
         fill = _html_color(colors=[fill], alpha=alpha)[0]
 
diff --git a/gt_extras/html.py b/gt_extras/html.py
index d3cff79..91b3de5 100644
--- a/gt_extras/html.py
+++ b/gt_extras/html.py
@@ -70,7 +70,7 @@ def with_tooltip(
         An HTML string containing the formatted tooltip element.
     """
 
-    # Throw if `text_decoration_style` is not one of the three allowed values
+    # Throw if `text_decoration_style` is not one of the allowed values
     if text_decoration_style not in [None, "solid", "dotted"]:
         raise ValueError("Text_decoration_style must be one of `None`, 'solid', or 'dotted'")
 
diff --git a/gt_extras/icons.py b/gt_extras/icons.py
index 03c8477..0023b5b 100644
--- a/gt_extras/icons.py
+++ b/gt_extras/icons.py
@@ -105,6 +105,10 @@ def fa_icon_repeat(
     --------
     See `icon_svg()` in the `faicons` package for further implementation details.
     """
+    # Throw if `a11y` is not one of the allowed values
+    if a11y not in [None, "deco", "sem"]:
+        raise ValueError("A11y must be one of `None`, 'deco', or 'sem'")
+
     if repeats < 0:
         raise ValueError("repeats must be >= 0")
 
diff --git a/gt_extras/plotting.py b/gt_extras/plotting.py
index 75b8f09..f2b6f07 100644
--- a/gt_extras/plotting.py
+++ b/gt_extras/plotting.py
@@ -114,6 +114,10 @@ def gt_plt_bar(
     """
     # A version with svg.py
 
+    # Throw if `scale_type` is not one of the allowed values
+    if scale_type not in [None, "percent", "number"]:
+        raise ValueError("Scale_type must be one of `None`, 'percent', or 'number'")
+
     if bar_height > height:
         bar_height = height
         warnings.warn(
@@ -186,7 +190,7 @@ def _make_bar_html(
     if stroke_color is None:
         stroke_color = "#FFFFFF00"
 
-    def make_bar(scaled_val: int, original_val: int) -> str:
+    def _make_bar(scaled_val: int, original_val: int) -> str:
         return _make_bar_html(
             scaled_val=scaled_val,
             original_val=original_val,
@@ -215,7 +219,7 @@ def make_bar(scaled_val: int, original_val: int) -> str:
         # Apply the scaled value for each row, so the bar is proportional
         for i, scaled_val in enumerate(scaled_vals):
             res = res.fmt(
-                lambda original_val, scaled_val=scaled_val: make_bar(
+                lambda original_val, scaled_val=scaled_val: _make_bar(
                     original_val=original_val,
                     scaled_val=scaled_val,
                 ),
diff --git a/gt_extras/tests/test_colors.py b/gt_extras/tests/test_colors.py
index d864de1..c2e5ef5 100644
--- a/gt_extras/tests/test_colors.py
+++ b/gt_extras/tests/test_colors.py
@@ -22,6 +22,20 @@ def test_gt_highlight_cols_alpha(mini_gt):
     assert "#80bcd833" in html
 
 
+def test_gt_highlight_cols_font_weight_invalid_string(mini_gt):
+    with pytest.raises(
+        ValueError,
+        match="Font_weight must be one of 'normal', 'bold', 'bolder', or 'lighter', or an integer",
+    ):
+        gt_highlight_cols(mini_gt, font_weight="invalid")
+
+
+@pytest.mark.parametrize("invalid_weight", [(1.5, 5), [], {}, None])
+def test_gt_highlight_cols_font_weight_invalid_type(mini_gt, invalid_weight):
+    with pytest.raises(TypeError, match="Font_weight must be an int, float, or str"):
+        gt_highlight_cols(mini_gt, font_weight=invalid_weight)
+
+
 def test_gt_hulk_col_numeric_snap(snapshot, mini_gt):
     res = gt_hulk_col_numeric(mini_gt)
     assert_rendered_body(snapshot, gt=res)
diff --git a/gt_extras/tests/test_html.py b/gt_extras/tests/test_html.py
index 2fcb13f..1507ca7 100644
--- a/gt_extras/tests/test_html.py
+++ b/gt_extras/tests/test_html.py
@@ -3,39 +3,48 @@
 from great_tables import GT
 from gt_extras.html import gt_hyperlink, with_tooltip
 
+
 def test_gt_hyperlink_basic():
     result = gt_hyperlink("Google", "https://google.com")
     expected = '<a href="https://google.com" target="_blank">Google</a>'
     assert result == expected
 
+
 def test_gt_hyperlink_new_tab_false():
     result = gt_hyperlink("Google", "https://google.com", new_tab=False)
     expected = '<a href="https://google.com" target="_self">Google</a>'
     assert result == expected
 
+
 def test_gt_hyperlink_new_tab_true():
     result = gt_hyperlink("GitHub", "https://github.com", new_tab=True)
     expected = '<a href="https://github.com" target="_blank">GitHub</a>'
     assert result == expected
 
+
 def test_gt_hyperlink_empty_text():
     result = gt_hyperlink("", "https://example.com")
     expected = '<a href="https://example.com" target="_blank"></a>'
     assert result == expected
 
+
 def test_gt_hyperlink_in_table():
-    df = pd.DataFrame({
-        "Name": ["Google", "GitHub"],
-        "Link": [
-            gt_hyperlink("Visit Google", "https://google.com"),
-            gt_hyperlink("View GitHub", "https://github.com", new_tab=False)
-        ]
-    })
-    
+    df = pd.DataFrame(
+        {
+            "Name": ["Google", "GitHub"],
+            "Link": [
+                gt_hyperlink("Visit Google", "https://google.com"),
+                gt_hyperlink("View GitHub", "https://github.com", new_tab=False),
+            ],
+        }
+    )
+
     gt_table = GT(df)
     html_output = gt_table.as_raw_html()
-    
-    assert '<a href="https://google.com" target="_blank">Visit Google</a>' in html_output
+
+    assert (
+        '<a href="https://google.com" target="_blank">Visit Google</a>' in html_output
+    )
     assert "https://github.com" in html_output
     assert 'target="_blank"' in html_output
     assert 'target="_self"' in html_output
@@ -46,40 +55,49 @@ def test_with_tooltip_basic():
     expected = '<abbr style="cursor: help; text-decoration: underline; text-decoration-style: dotted; color: blue; " title="Number One">1</abbr>'
     assert result == expected
 
+
 def test_with_tooltip_underline_style():
     result = with_tooltip("1", "Number One", text_decoration_style="solid")
     expected = '<abbr style="cursor: help; text-decoration: underline; text-decoration-style: solid; color: blue; " title="Number One">1</abbr>'
     assert result == expected
 
+
 def test_with_tooltip_underline_fail():
     with pytest.raises(ValueError):
         with_tooltip("1", "Number One", text_decoration_style="underline")
 
+
 def test_with_tooltip_no_decoration():
     result = with_tooltip("1", "Number One", text_decoration_style=None)
     expected = '<abbr style="cursor: help; text-decoration: none; color: blue; " title="Number One">1</abbr>'
     assert result == expected
 
+
 def test_with_tooltip_no_color():
     result = with_tooltip("1", "Number One", color=None)
     expected = '<abbr style="cursor: help; text-decoration: underline; text-decoration-style: dotted; " title="Number One">1</abbr>'
     assert result == expected
 
-def test_with_tooltip_in_table():    
-    df = pd.DataFrame({
-        "Number": ["1", "2"],
-        "Description": [
-            with_tooltip("1", "Number One"),
-            with_tooltip("2", "Number Two", text_decoration_style="solid", color="red")
-        ]
-    })
-    
+
+def test_with_tooltip_in_table():
+    df = pd.DataFrame(
+        {
+            "Number": ["1", "2"],
+            "Description": [
+                with_tooltip("1", "Number One"),
+                with_tooltip(
+                    "2", "Number Two", text_decoration_style="solid", color="red"
+                ),
+            ],
+        }
+    )
+
     html_output = GT(df).as_raw_html()
-    
+
     assert 'title="Number One"' in html_output
     assert 'title="Number Two"' in html_output
-    assert 'cursor: help' in html_output
-    assert 'text-decoration-style: dotted' in html_output
-    assert 'text-decoration-style: solid' in html_output
-    assert 'color: blue' in html_output
-    assert 'color: red' in html_output
\ No newline at end of file
+    assert "cursor: help" in html_output
+    assert "text-decoration-style: dotted" in html_output
+    assert "text-decoration-style: solid" in html_output
+    assert "color: blue" in html_output
+    assert "color: red" in html_output
diff --git a/gt_extras/tests/test_icons.py b/gt_extras/tests/test_icons.py
index 24f6c62..9593397 100644
--- a/gt_extras/tests/test_icons.py
+++ b/gt_extras/tests/test_icons.py
@@ -135,3 +135,10 @@ def test_gt_fa_rating_multiple_columns():
 
     assert html.count("<svg") == 20
     assert "out of 5" in html
+
+
+def test_fa_icon_repeat_a11y_invalid_string():
+    with pytest.raises(
+        ValueError, match="A11y must be one of `None`, 'deco', or 'sem'"
+    ):
+        fa_icon_repeat(a11y="invalid")
diff --git a/gt_extras/tests/test_plotting.py b/gt_extras/tests/test_plotting.py
index d556c70..923a0a8 100644
--- a/gt_extras/tests/test_plotting.py
+++ b/gt_extras/tests/test_plotting.py
@@ -64,6 +64,13 @@ def test_gt_plt_bar_no_stroke_color(mini_gt):
     assert html.count("#FFFFFF00") == 3
 
 
+def test_gt_plt_bar_scale_type_invalid_string(mini_gt):
+    with pytest.raises(
+        ValueError, match="Scale_type must be one of `None`, 'percent', or 'number'"
+    ):
+        gt_plt_bar(mini_gt, scale_type="invalid")
+
+
 def test_gt_plt_bar_type_error(mini_gt):
     with pytest.raises(TypeError, match="Invalid column type provided"):
         gt_plt_bar(gt=mini_gt, columns=["char"]).as_raw_html()
diff --git a/gt_extras/tests/test_themes.py b/gt_extras/tests/test_themes.py
index e9c5558..6a1d05b 100644
--- a/gt_extras/tests/test_themes.py
+++ b/gt_extras/tests/test_themes.py
@@ -22,59 +22,71 @@ def test_theme_538_fonts_snap(snapshot, mini_gt):
     themed_gt = gt_theme_538(gt=mini_gt)
     assert_rendered_global_imports(snapshot, themed_gt)
 
+
 def test_theme_espn_fonts_snap(snapshot, mini_gt):
     themed_gt = gt_theme_espn(gt=mini_gt)
     assert_rendered_global_imports(snapshot, themed_gt)
 
+
 def test_theme_nytimes_fonts_snap(snapshot, mini_gt):
     themed_gt = gt_theme_nytimes(gt=mini_gt)
     assert_rendered_global_imports(snapshot, themed_gt)
 
+
 def test_theme_guardian_fonts_snap(snapshot, mini_gt):
     themed_gt = gt_theme_guardian(gt=mini_gt)
     assert_rendered_global_imports(snapshot, themed_gt)
 
+
 def test_theme_excel_fonts_snap(snapshot, mini_gt):
     themed_gt = gt_theme_excel(gt=mini_gt)
     assert_rendered_global_imports(snapshot, themed_gt)
 
+
 def test_theme_excel_color(mini_gt):
     themed_gt = gt_theme_excel(gt=mini_gt, color="lightblue")
     html = themed_gt.as_raw_html()
     assert "lightblue" in html
 
+
 def test_theme_dot_matrix_fonts_snap(snapshot, mini_gt):
     themed_gt = gt_theme_dot_matrix(gt=mini_gt)
     assert_rendered_global_imports(snapshot, themed_gt)
 
+
 def test_theme_dot_matrix_color(mini_gt):
     themed_gt = gt_theme_dot_matrix(gt=mini_gt, color="lightblue")
     html = themed_gt.as_raw_html()
     assert "lightblue" in html
 
+
 def test_theme_dark_fonts_snap(snapshot, mini_gt):
     themed_gt = gt_theme_dark(gt=mini_gt)
     assert_rendered_global_imports(snapshot, themed_gt)
 
+
 def test_theme_pff_fonts_snap(snapshot, mini_gt):
     themed_gt = gt_theme_pff(gt=mini_gt)
     assert_rendered_global_imports(snapshot, themed_gt)
 
+
 def test_theme_pff_dividers(mini_gt):
     themed_gt = gt_theme_pff(gt=mini_gt, divider="num")
     html = themed_gt.as_raw_html()
     print(html)
     assert "border-left: 2px solid lightgrey" in html
 
+
 def test_theme_pff_spanner(mini_gt):
     gt_with_spanner = mini_gt.tab_spanner("Spanner Label", columns=["num", "char"])
     themed_gt = gt_theme_pff(gt=gt_with_spanner, spanners=["Spanner Label"])
     html = themed_gt.as_raw_html()
-    assert "Spanner Label" in html 
+    assert "Spanner Label" in html
     # This assertion ensures the blank spanner is created
     assert '<span class="gt_column_spanner"> </span>' in html
 
+
 def test_theme_pff_rank_col(mini_gt):
     themed_gt = gt_theme_pff(gt=mini_gt, rank_col="num")
     html = themed_gt.as_raw_html()
-    assert "#e4e8ec" in html
\ No newline at end of file
+    assert "#e4e8ec" in html