diff --git a/CHANGELOG.md b/CHANGELOG.md
index 75bf2b7c7..0d82e48c2 100644
--- a/CHANGELOG.md
+++ b/CHANGELOG.md
@@ -7,6 +7,16 @@ and this project adheres to [Semantic Versioning](http://semver.org/).
 
 ## Unreleased
 
+### Fixed
+
+- Fixed `!important` not applying to `align` https://github.com/Textualize/textual/issues/2420
+- Fixed `!important` not applying to `border` https://github.com/Textualize/textual/issues/2420
+- Fixed `!important` not applying to `content-align` https://github.com/Textualize/textual/issues/2420
+- Fixed `!important` not applying to `outline` https://github.com/Textualize/textual/issues/2420
+- Fixed `!important` not applying to `overflow` https://github.com/Textualize/textual/issues/2420
+- Fixed `!important` not applying to `scrollbar-size` https://github.com/Textualize/textual/issues/2420
+- Fixed `outline-right` not being recognised https://github.com/Textualize/textual/issues/2446
+
 ### Changed
 
 - Setting attributes with a `compute_` method will now raise an `AttributeError` https://github.com/Textualize/textual/issues/2383
diff --git a/src/textual/css/_styles_builder.py b/src/textual/css/_styles_builder.py
index 4e6ddcc1d..f38506311 100644
--- a/src/textual/css/_styles_builder.py
+++ b/src/textual/css/_styles_builder.py
@@ -252,6 +252,23 @@ class StylesBuilder:
         else:
             scalar_error()
 
+    def _distribute_importance(self, prefix: str, suffixes: tuple[str, ...]) -> None:
+        """Distribute importance amongst all aspects of the given style.
+
+        Args:
+            prefix: The prefix of the style.
+            siffixes: The suffixes to distribute amongst.
+
+        A number of styles can be set with the 'prefix' of the style,
+        providing the values as a series of parameters; or they can be set
+        with specific suffixes. Think `border` vs `border-left`, etc. This
+        method is used to ensure that if the former is set, `!important` is
+        distributed amongst all the suffixes.
+        """
+        if prefix in self.styles.important:
+            self.styles.important.remove(prefix)
+            self.styles.important.update(f"{prefix}_{suffix}" for suffix in suffixes)
+
     def process_box_sizing(self, name: str, tokens: list[Token]) -> None:
         for token in tokens:
             name, value, _, _, location, _ = token
@@ -304,6 +321,7 @@ class StylesBuilder:
         )
         rules["overflow_x"] = cast(Overflow, overflow_x)
         rules["overflow_y"] = cast(Overflow, overflow_y)
+        self._distribute_importance("overflow", ("x", "y"))
 
     def process_overflow_x(self, name: str, tokens: list[Token]) -> None:
         self.styles._rules["overflow_x"] = cast(
@@ -486,6 +504,7 @@ class StylesBuilder:
         rules = self.styles._rules
         rules["border_top"] = rules["border_right"] = border
         rules["border_bottom"] = rules["border_left"] = border
+        self._distribute_importance("border", ("top", "left", "bottom", "right"))
 
     def process_border_top(self, name: str, tokens: list[Token]) -> None:
         self._process_border_edge("top", name, tokens)
@@ -508,11 +527,12 @@ class StylesBuilder:
         rules = self.styles._rules
         rules["outline_top"] = rules["outline_right"] = border
         rules["outline_bottom"] = rules["outline_left"] = border
+        self._distribute_importance("outline", ("top", "left", "bottom", "right"))
 
     def process_outline_top(self, name: str, tokens: list[Token]) -> None:
         self._process_outline("top", name, tokens)
 
-    def process_parse_border_right(self, name: str, tokens: list[Token]) -> None:
+    def process_outline_right(self, name: str, tokens: list[Token]) -> None:
         self._process_outline("right", name, tokens)
 
     def process_outline_bottom(self, name: str, tokens: list[Token]) -> None:
@@ -792,6 +812,8 @@ class StylesBuilder:
         self.styles._rules[f"{name}_horizontal"] = token_horizontal.value  # type: ignore
         self.styles._rules[f"{name}_vertical"] = token_vertical.value  # type: ignore
 
+        self._distribute_importance(name, ("horizontal", "vertical"))
+
     def process_align_horizontal(self, name: str, tokens: list[Token]) -> None:
         try:
             value = self._process_enum(name, tokens, VALID_ALIGN_HORIZONTAL)
@@ -859,6 +881,7 @@ class StylesBuilder:
                 scrollbar_size_error(name, token2)
             self.styles._rules["scrollbar_size_horizontal"] = horizontal
             self.styles._rules["scrollbar_size_vertical"] = vertical
+            self._distribute_importance("scrollbar_size", ("horizontal", "vertical"))
 
     def process_scrollbar_size_vertical(self, name: str, tokens: list[Token]) -> None:
         if not tokens:
diff --git a/tests/test_style_importance.py b/tests/test_style_importance.py
new file mode 100644
index 000000000..fc5547416
--- /dev/null
+++ b/tests/test_style_importance.py
@@ -0,0 +1,102 @@
+from textual.app import App, ComposeResult
+from textual.color import Color
+from textual.containers import Container
+from textual.css.scalar import Scalar, ScalarOffset
+
+
+class StyleApp(App[None]):
+    CSS = """
+    Container {
+        border: round green !important;
+        outline: round green !important;
+        align: right bottom !important;
+        content-align: right bottom !important;
+        offset: 17 23 !important;
+        overflow: hidden hidden !important;
+        padding: 10 20 30 40 !important;
+        scrollbar-size: 23 42 !important;
+    }
+
+    Container.more-specific {
+        border: solid red;
+        outline: solid red;
+        align: center middle;
+        content-align: center middle;
+        offset: 0 0;
+        overflow: scroll scroll;
+        padding: 1 2 3 4;
+        scrollbar-size: 1 2;
+    }
+    """
+
+    def compose(self) -> ComposeResult:
+        yield Container(classes="more-specific")
+
+
+async def test_border_importance():
+    """Border without sides should support !important"""
+    async with StyleApp().run_test() as pilot:
+        border = pilot.app.query_one(Container).styles.border
+        desired = ("round", Color.parse("green"))
+        assert border.top == desired
+        assert border.left == desired
+        assert border.bottom == desired
+        assert border.right == desired
+
+
+async def test_outline_importance():
+    """Outline without sides should support !important"""
+    async with StyleApp().run_test() as pilot:
+        outline = pilot.app.query_one(Container).styles.outline
+        desired = ("round", Color.parse("green"))
+        assert outline.top == desired
+        assert outline.left == desired
+        assert outline.bottom == desired
+        assert outline.right == desired
+
+
+async def test_align_importance():
+    """Align without direction should support !important"""
+    async with StyleApp().run_test() as pilot:
+        assert pilot.app.query_one(Container).styles.align == ("right", "bottom")
+
+
+async def test_content_align_importance():
+    """Content align without direction should support !important"""
+    async with StyleApp().run_test() as pilot:
+        assert pilot.app.query_one(Container).styles.content_align == (
+            "right",
+            "bottom",
+        )
+
+
+async def test_offset_importance():
+    """Offset without direction should support !important"""
+    async with StyleApp().run_test() as pilot:
+        assert pilot.app.query_one(Container).styles.offset == ScalarOffset.from_offset(
+            (17, 23)
+        )
+
+
+async def test_overflow_importance():
+    """Overflow without direction should support !important"""
+    async with StyleApp().run_test() as pilot:
+        assert pilot.app.query_one(Container).styles.overflow_x == "hidden"
+        assert pilot.app.query_one(Container).styles.overflow_y == "hidden"
+
+
+async def test_padding_importance():
+    """Padding without sides should support !important"""
+    async with StyleApp().run_test() as pilot:
+        padding = pilot.app.query_one(Container).styles.padding
+        assert padding.top == 10
+        assert padding.left == 40
+        assert padding.bottom == 30
+        assert padding.right == 20
+
+
+async def test_scrollbar_size_importance():
+    """Scrollbar size without direction should support !important"""
+    async with StyleApp().run_test() as pilot:
+        assert pilot.app.query_one(Container).styles.scrollbar_size_horizontal == 23
+        assert pilot.app.query_one(Container).styles.scrollbar_size_vertical == 42