diff --git a/fpdf/drawing.py b/fpdf/drawing.py
index c0dcd8aaf..221dd4d1f 100644
--- a/fpdf/drawing.py
+++ b/fpdf/drawing.py
@@ -271,7 +271,7 @@ def colors255(self):
         return tuple(255 * v for v in self.colors)
 
     def serialize(self) -> str:
-        return f"{0 if self.g == 0 else self.g} {self.OPERATOR}"
+        return f"{number_to_str(self.g)} {self.OPERATOR}"
 
 
 __pdoc__["DeviceGray.OPERATOR"] = False
diff --git a/fpdf/enums.py b/fpdf/enums.py
index 0002669c3..1db0abdf1 100644
--- a/fpdf/enums.py
+++ b/fpdf/enums.py
@@ -227,6 +227,9 @@ class TextEmphasis(CoerciveIntFlag):
         style = B | I
     """
 
+    NONE = 0
+    "No emphasis"
+
     B = 1
     "Bold"
 
@@ -246,7 +249,7 @@ def style(self):
     def coerce(cls, value):
         if isinstance(value, str):
             if value == "":
-                return 0
+                return cls.NONE
             if value.upper() == "BOLD":
                 return cls.B
             if value.upper() == "ITALICS":
diff --git a/fpdf/fonts.py b/fpdf/fonts.py
index 87379f48e..6d93a796d 100644
--- a/fpdf/fonts.py
+++ b/fpdf/fonts.py
@@ -51,7 +51,9 @@ class FontFace:
         "fill_color",
     )
     family: Optional[str]
-    emphasis: Optional[TextEmphasis]  # can be a combination: B | U
+    emphasis: Optional[TextEmphasis]  # None means "no override"
+    #                                   Whereas "" means "no emphasis"
+    #                                   This can be a combination: B | U
     size_pt: Optional[int]
     # Colors are single number grey scales or (red, green, blue) tuples:
     color: Optional[Union[DeviceGray, DeviceRGB]]
@@ -61,7 +63,7 @@ def __init__(
         self, family=None, emphasis=None, size_pt=None, color=None, fill_color=None
     ):
         self.family = family
-        self.emphasis = TextEmphasis.coerce(emphasis) if emphasis else None
+        self.emphasis = None if emphasis is None else TextEmphasis.coerce(emphasis)
         self.size_pt = size_pt
         self.color = None if color is None else convert_to_device_color(color)
         self.fill_color = (
diff --git a/fpdf/fpdf.py b/fpdf/fpdf.py
index f1512bef2..35e24b6ba 100644
--- a/fpdf/fpdf.py
+++ b/fpdf/fpdf.py
@@ -144,7 +144,8 @@ class Image:
 class TitleStyle(FontFace):
     def __init__(
         self,
-        font_family: Optional[str] = None,
+        font_family: Optional[str] = None,  # None means "no override"
+        #                                     Whereas "" means "no emphasis"
         font_style: Optional[str] = None,
         font_size_pt: Optional[int] = None,
         color: Union[int, tuple] = None,  # grey scale or (red, green, blue),
@@ -155,7 +156,7 @@ def __init__(
     ):
         super().__init__(
             font_family,
-            (font_style or "") + ("U" if underline else ""),
+            ((font_style or "") + "U") if underline else font_style,
             font_size_pt,
             color,
         )
diff --git a/test/drawing/test_drawing.py b/test/drawing/test_drawing.py
index 57d92ba6e..a3155f9a6 100644
--- a/test/drawing/test_drawing.py
+++ b/test/drawing/test_drawing.py
@@ -148,8 +148,8 @@ def test_device_gray(self):
         gray = fpdf.drawing.DeviceGray(g=0.5)
         gray_a = fpdf.drawing.DeviceGray(g=0.5, a=0.75)
 
-        assert gray.colors == (0.5,)
-        assert gray_a.colors == (0.5,)
+        assert gray.colors == (0.5, 0.5, 0.5)
+        assert gray_a.colors == (0.5, 0.5, 0.5)
 
         with pytest.raises(ValueError):
             fpdf.drawing.DeviceGray(g=2)
diff --git a/test/outline/test_outline.py b/test/outline/test_outline.py
index 837c9e8ff..aa07bb535 100644
--- a/test/outline/test_outline.py
+++ b/test/outline/test_outline.py
@@ -173,9 +173,20 @@ def test_toc_with_font_style_override_bold(tmp_path):  # issue-1072
     pdf = FPDF()
     pdf.add_page()
     pdf.set_font("Helvetica", "B")
-    pdf.set_section_title_styles(TitleStyle("Helvetica", "", 20, (0, 0, 0)))
+    pdf.set_section_title_styles(
+        TitleStyle("Helvetica", font_size_pt=20, color=(0, 0, 0))
+    )
+    pdf.start_section("foo")
+    assert_pdf_equal(pdf, HERE / "toc_with_font_style_override_bold1.pdf", tmp_path)
+
+    pdf = FPDF()
+    pdf.add_page()
+    pdf.set_font("Helvetica", "B")
+    pdf.set_section_title_styles(
+        TitleStyle("Helvetica", font_style="", font_size_pt=20, color=(0, 0, 0))
+    )
     pdf.start_section("foo")
-    assert_pdf_equal(pdf, HERE / "toc_with_font_style_override_bold.pdf", tmp_path)
+    assert_pdf_equal(pdf, HERE / "toc_with_font_style_override_bold2.pdf", tmp_path)
 
 
 def test_toc_with_table(tmp_path):  # issue-1079
diff --git a/test/outline/toc_with_font_style_override_bold.pdf b/test/outline/toc_with_font_style_override_bold1.pdf
similarity index 62%
rename from test/outline/toc_with_font_style_override_bold.pdf
rename to test/outline/toc_with_font_style_override_bold1.pdf
index a32fbc162..e3fab61ef 100644
Binary files a/test/outline/toc_with_font_style_override_bold.pdf and b/test/outline/toc_with_font_style_override_bold1.pdf differ