Swap the checkbox to using an actual check mark

src/textual/widgets/_checkbox.py

@@ -1,5 +1,7 @@
 """Provides a check box widget."""
 
+from __future__ import annotations
+
 from ._toggle import ToggleButton
 
 
@@ -11,3 +13,26 @@ class Checkbox(ToggleButton):
 
         # https://github.com/Textualize/textual/issues/1814
         namespace = "checkbox"
+
+    def __init__(
+        self,
+        label: str,
+        value: bool = False,
+        button_first: bool = True,
+        *,
+        name: str | None = None,
+        id: str | None = None,
+        classes: str | None = None,
+    ):
+        """Initialise the radio button.
+
+        Args:
+            label: The label for the toggle.
+            value: The initial value of the checkbox. Defaults to `False`.
+            button_first: Should the button come before the label, or after?
+            name: The name of the checkbox.
+            id: The ID of the checkbox in the DOM.
+            classes: The CSS classes of the checkbox.
+        """
+        super().__init__(label, value, button_first, name=name, id=id, classes=classes)
+        self.button_on = "✓"