diff --git a/Sources/Ignite/Elements/Slide.swift b/Sources/Ignite/Elements/Slide.swift
index ca0f5092..e473f81c 100644
--- a/Sources/Ignite/Elements/Slide.swift
+++ b/Sources/Ignite/Elements/Slide.swift
@@ -72,7 +72,7 @@ public struct Slide: BlockHTML {
                     .style(
                         .init(.height, value: "100%"),
                         .init(.objectFit, value: "cover"),
-                        .init(.opacity, value: backgroundOpacity.formatted())
+                        .init(.opacity, value: backgroundOpacity.formatted(.nonLocalizedDecimal))
                     )
             }
 
diff --git a/Sources/Ignite/Extensions/FormatStyle-NonLocalizedDecimal.swift b/Sources/Ignite/Extensions/FormatStyle-NonLocalizedDecimal.swift
new file mode 100644
index 00000000..b2db0a76
--- /dev/null
+++ b/Sources/Ignite/Extensions/FormatStyle-NonLocalizedDecimal.swift
@@ -0,0 +1,42 @@
+//
+// FormatStyle-NonLocalizedDecimal.swift
+// Ignite
+// https://www.github.com/twostraws/Ignite
+// See LICENSE for license information.
+//
+
+import Foundation
+
+extension FormatStyle where Self == FloatingPointFormatStyle<Double>, FormatInput == Double {
+    /// A format style that displays a floating point number with one decimal place,
+    /// enforcing the use of a `.` as the decimal separator.
+    static var nonLocalizedDecimal: Self {
+        nonLocalizedDecimal(places: 1)
+    }
+
+    /// A format style that displays a floating point number enforcing the use of a `.` as the decimal separator.
+    /// - Parameter places: The number of decimal places to display. Defaults to 1.
+    static func nonLocalizedDecimal(places: Int = 1) -> Self {
+        let precision = max(0, places)
+        return FloatingPointFormatStyle()
+            .precision(.fractionLength(0...precision))
+            .locale(Locale(identifier: "en_US"))
+    }
+}
+
+extension FormatStyle where Self == FloatingPointFormatStyle<Float>, FormatInput == Float {
+    /// A format style that displays a floating point number with one decimal place,
+    /// enforcing the use of a `.` as the decimal separator.
+    static var nonLocalizedDecimal: Self {
+        nonLocalizedDecimal(places: 1)
+    }
+
+    /// A format style that displays a floating point number enforcing the use of a `.` as the decimal separator.
+    /// - Parameter places: The number of decimal places to display. Defaults to 1.
+    static func nonLocalizedDecimal(places: Int = 1) -> Self {
+        let precision = max(0, places)
+        return FloatingPointFormatStyle()
+            .precision(.fractionLength(0...precision))
+            .locale(Locale(identifier: "en_US"))
+    }
+}
diff --git a/Sources/Ignite/Modifiers/LineSpacing.swift b/Sources/Ignite/Modifiers/LineSpacing.swift
index bd19b75a..beb73f81 100644
--- a/Sources/Ignite/Modifiers/LineSpacing.swift
+++ b/Sources/Ignite/Modifiers/LineSpacing.swift
@@ -28,13 +28,13 @@ struct LineSpacingModifier: HTMLModifier {
     func body(content: some HTML) -> any HTML {
         if content.body.isComposite {
             if let customHeight {
-                content.containerStyle(.init(.lineHeight, value: customHeight.formatted()))
+                content.containerStyle(.init(.lineHeight, value: customHeight.formatted(.nonLocalizedDecimal)))
             } else if let presetHeight {
                 content.containerClass("lh-\(presetHeight.rawValue)")
             }
         } else {
             if let customHeight {
-                content.style(.init(.lineHeight, value: customHeight.formatted()))
+                content.style(.init(.lineHeight, value: customHeight.formatted(.nonLocalizedDecimal)))
             } else if let presetHeight {
                 content.class("lh-\(presetHeight.rawValue)")
             }
diff --git a/Sources/Ignite/Modifiers/Opacity.swift b/Sources/Ignite/Modifiers/Opacity.swift
index c72f2bfd..f291da47 100644
--- a/Sources/Ignite/Modifiers/Opacity.swift
+++ b/Sources/Ignite/Modifiers/Opacity.swift
@@ -5,6 +5,8 @@
 // See LICENSE for license information.
 //
 
+import Foundation
+
 /// A modifier that applies opacity styling to HTML elements
 struct OpacityModifier: HTMLModifier {
     /// The opacity value between 0% (transparent) and 100% (opaque)
@@ -32,9 +34,9 @@ struct OpacityModifier: HTMLModifier {
     /// - Returns: The modified HTML with opacity applied
     func body(content: some HTML) -> any HTML {
         if let percentage, percentage != 100% {
-            content.style(.opacity, percentage.value.formatted())
+            content.style(.opacity, percentage.value.formatted(.nonLocalizedDecimal(places: 3)))
         } else if let doubleValue, doubleValue != 1 {
-            content.style(.opacity, doubleValue.formatted())
+            content.style(.opacity, doubleValue.formatted(.nonLocalizedDecimal(places: 3)))
         }
         content
     }
diff --git a/Tests/IgniteTesting/Modifiers/Opacity.swift b/Tests/IgniteTesting/Modifiers/Opacity.swift
index 43657183..6b0156d5 100644
--- a/Tests/IgniteTesting/Modifiers/Opacity.swift
+++ b/Tests/IgniteTesting/Modifiers/Opacity.swift
@@ -33,4 +33,26 @@ struct OpacityTests {
 
         #expect(output == "<img alt=\"\(image.description)\" src=\"\(image.path)\" style=\"opacity: 0.2\" />")
     }
+
+    @Test("Checks that the opacity value is correctly formatted", arguments: [
+        (value: 0.123456, expected: "0.123"),
+        (value: 0.15, expected: "0.15"),
+        (value: 0.1, expected: "0.1"),
+        (value: 0.45678, expected: "0.457"),
+        (value: 0, expected: "0")
+    ])
+    func opacityFormatting(testCase: (value: Double, expected: String)) async throws {
+        let element = Text("Test").opacity(testCase.value)
+        let output = element.render()
+
+        #expect(output == "<p style=\"opacity: \(testCase.expected)\">Test</p>")
+    }
+
+    @Test("Checks that full opacity is not rendered")
+    func fullOpacity() async throws {
+        let element = Text("Test").opacity(1)
+        let output = element.render()
+
+        #expect(output == "<p>Test</p>")
+    }
 }