diff --git a/Sources/CSS/Properties/Margin.swift b/Sources/CSS/Properties/Margin.swift
index 1e7f17c..e14a7b0 100644
--- a/Sources/CSS/Properties/Margin.swift
+++ b/Sources/CSS/Properties/Margin.swift
@@ -56,27 +56,27 @@ public struct Margin: Property {
     /// Creates a `margin` declaration.
     /// Used by `StylesheetRenderer` when emitting CSS.
     /// - Parameters:
-    ///   - horizontal: The horizontal value.
     ///   - vertical: The vertical value.
+    ///   - horizontal: The horizontal value.
     public init(
-        horizontal: Value,
-        vertical: Value
+        vertical: Value,
+        horizontal: Value
     ) {
         self.name = "margin"
-        self.value = horizontal.rawValue + " " + vertical.rawValue
+        self.value = vertical.rawValue + " " + horizontal.rawValue
         self.isImportant = false
     }
 
     /// Creates a `margin` declaration.
     /// Used by `StylesheetRenderer` when emitting CSS.
     /// - Parameters:
-    ///   - horizontal: The horizontal value.
     ///   - vertical: The vertical value.
+    ///   - horizontal: The horizontal value.
     public init(
-        horizontal: UnitRepresentable = 0,
-        vertical: UnitRepresentable = 0
+        vertical: UnitRepresentable = 0,
+        horizontal: UnitRepresentable = 0
     ) {
-        self.init(horizontal: .length(horizontal), vertical: .length(vertical))
+        self.init(vertical: .length(vertical), horizontal: .length(horizontal))
     }
 
     /// Creates a `margin` declaration.
diff --git a/Sources/CSS/Properties/Padding.swift b/Sources/CSS/Properties/Padding.swift
index 3309a9b..faf6a24 100644
--- a/Sources/CSS/Properties/Padding.swift
+++ b/Sources/CSS/Properties/Padding.swift
@@ -52,27 +52,27 @@ public struct Padding: Property {
     /// Creates a `padding` declaration.
     /// Used by `StylesheetRenderer` when emitting CSS.
     /// - Parameters:
-    ///   - horizontal: The horizontal value.
     ///   - vertical: The vertical value.
+    ///   - horizontal: The horizontal value.
     public init(
-        horizontal: Value,
-        vertical: Value
+        vertical: Value,
+        horizontal: Value
     ) {
         self.name = "padding"
-        self.value = horizontal.rawValue + " " + vertical.rawValue
+        self.value = vertical.rawValue + " " + horizontal.rawValue
         self.isImportant = false
     }
 
     /// Creates a `padding` declaration.
     /// Used by `StylesheetRenderer` when emitting CSS.
     /// - Parameters:
-    ///   - horizontal: The horizontal value.
     ///   - vertical: The vertical value.
+    ///   - horizontal: The horizontal value.
     public init(
-        horizontal: UnitRepresentable = 0,
-        vertical: UnitRepresentable = 0
+        vertical: UnitRepresentable = 0,
+        horizontal: UnitRepresentable = 0
     ) {
-        self.init(horizontal: .length(horizontal), vertical: .length(vertical))
+        self.init(vertical: .length(vertical), horizontal: .length(horizontal))
     }
 
     /// Creates a `padding` declaration.
diff --git a/Tests/CSSTests/Properties/MarginTestSuite.swift b/Tests/CSSTests/Properties/MarginTestSuite.swift
index 2bd3ed1..3ae7489 100644
--- a/Tests/CSSTests/Properties/MarginTestSuite.swift
+++ b/Tests/CSSTests/Properties/MarginTestSuite.swift
@@ -39,7 +39,7 @@ struct MarginTests {
     @Test
     func values() {
         let single = Margin(12.px)
-        let axis = Margin(horizontal: 8.px, vertical: 16.px)
+        let axis = Margin(vertical: 8.px, horizontal: 16.px)
         let sides = Margin(top: 1.px, right: 2.px, bottom: 3.px, left: 4.px)
         let auto = Margin(.auto)
         let initial = Margin(.initial)
diff --git a/Tests/CSSTests/Properties/PaddingTestSuite.swift b/Tests/CSSTests/Properties/PaddingTestSuite.swift
index 2992ab0..19b8988 100644
--- a/Tests/CSSTests/Properties/PaddingTestSuite.swift
+++ b/Tests/CSSTests/Properties/PaddingTestSuite.swift
@@ -39,7 +39,7 @@ struct PaddingTests {
     @Test
     func values() {
         let single = Padding(12.px)
-        let axis = Padding(horizontal: 8.px, vertical: 16.px)
+        let axis = Padding(vertical: 8.px, horizontal: 16.px)
         let sides = Padding(top: 1.px, right: 2.px, bottom: 3.px, left: 4.px)
         let inherit = Padding(.inherit)
 
diff --git a/Tests/CSSTests/SelectorTests.swift b/Tests/CSSTests/SelectorTests.swift
index 5115928..e76cad4 100644
--- a/Tests/CSSTests/SelectorTests.swift
+++ b/Tests/CSSTests/SelectorTests.swift
@@ -55,8 +55,8 @@ struct SelectorTests {
                 AllElements {
                     Padding(0)
                     Padding(8.rem)
-                    Padding(horizontal: 8.px)
-                    Padding(horizontal: .length(0), vertical: .inherit)
+                    Padding(vertical: 8.px)
+                    Padding(vertical: .length(0), horizontal: .inherit)
                 }
             }
         }
diff --git a/Tests/CSSTests/StylesheetRendererTests.swift b/Tests/CSSTests/StylesheetRendererTests.swift
index 467a69b..910a22d 100644
--- a/Tests/CSSTests/StylesheetRendererTests.swift
+++ b/Tests/CSSTests/StylesheetRendererTests.swift
@@ -16,7 +16,7 @@ struct StylesheetRendererTests {
         let css = Stylesheet {
             Media {
                 Class("badge") {
-                    Padding(horizontal: 6.px, vertical: 2.px)
+                    Padding(vertical: 6.px, horizontal: 2.px)
                     BackgroundColor(.red)
                 }
             }
diff --git a/Tests/CSSTests/SwiftCSSTests.swift b/Tests/CSSTests/SwiftCSSTests.swift
index 131f429..63926cb 100644
--- a/Tests/CSSTests/SwiftCSSTests.swift
+++ b/Tests/CSSTests/SwiftCSSTests.swift
@@ -17,14 +17,14 @@ struct SwiftCssTests {
             Charset("UTF-8")
             Media {
                 Root {
-                    Margin(horizontal: 8.5.px, vertical: 8.px)
-                    Padding(horizontal: 8.px, vertical: 8.px)
+                    Margin(vertical: 8.5.px, horizontal: 8.px)
+                    Padding(vertical: 8.5.px, horizontal: 8.px)
                 }
             }
         }
         #expect(
             StylesheetRenderer(minify: true, indent: 2).render(css)
-                == #"@charset "UTF-8";:root{margin:8.5px 8px;padding:8px 8px}"#
+                == #"@charset "UTF-8";:root{margin:8.5px 8px;padding:8.5px 8px}"#
         )
     }
 
@@ -34,8 +34,8 @@ struct SwiftCssTests {
             Charset("UTF-8")
             Media {
                 Root {
-                    Margin(horizontal: 8.5.px, vertical: 8.px)
-                    Padding(horizontal: 8.px, vertical: 8.px)
+                    Margin(vertical: 8.5.px, horizontal: 8.px)
+                    Padding(vertical: 8.5.px, horizontal: 8.px)
                 }
             }
         }
@@ -45,7 +45,7 @@ struct SwiftCssTests {
                 @charset "UTF-8";
                 :root {
                   margin: 8.5px 8px;
-                  padding: 8px 8px;
+                  padding: 8.5px 8px;
                 }
                 """#
         )
@@ -58,8 +58,8 @@ struct SwiftCssTests {
 
             Media {
                 Root {
-                    Margin(horizontal: 8.5.px, vertical: 8.px)
-                    Padding(horizontal: 8.px, vertical: 8.px)
+                    Margin(vertical: 8.5.px, horizontal: 8.px)
+                    Padding(vertical: 8.5.px, horizontal: 8.px)
                 }
             }
 
@@ -70,7 +70,7 @@ struct SwiftCssTests {
             }
             Media(.screen && .prefersColorScheme(.dark)) {
                 Universal {
-                    Margin(horizontal: 8.px, vertical: 8.px)
+                    Margin(vertical: 8.5.px, horizontal: 8.px)
                 }
             }
 
@@ -86,7 +86,7 @@ struct SwiftCssTests {
                 @charset "UTF-8";
                 :root {
                     margin: 8.5px 8px;
-                    padding: 8px 8px;
+                    padding: 8.5px 8px;
                 }
                 @media screen and (min-width: 600px) {
                     .button {
@@ -95,7 +95,7 @@ struct SwiftCssTests {
                 }
                 @media screen and (prefers-color-scheme: dark) {
                     * {
-                        margin: 8px 8px;
+                        margin: 8.5px 8px;
                     }
                 }
                 @media screen and (display-mode: standalone) {